Bug 1471814 - Add a preference for implicit keyframes; r=bz,hiro

This preference controls whether authors are allowed to specify animations without a 0% or 100% keyframe. We intend to ship this soon but this preference acts as a safeguard in case we discover we need to disable it. This feature is very convenient and commonly used so this patch ensures it is always enabled for system content. MozReview-Commit-ID: BHTsuS2xO61 --HG-- rename : dom/animation/test/mozilla/file_disable_animations_api_core.html => dom/animation/test/mozilla/file_disable_animations_api_implicit_keyframes.html rename : dom/animation/test/mozilla/test_disable_animations_api_core.html => dom/animation/test/mozilla/test_disable_animations_api_implicit_keyframes.html extra : rebase_source : 04fd93dd26a4765c14b0b22febdb0311b650ea59
2024-10-19 00:05:36 +00:00 · 2018-07-14 09:23:03 +09:00 · 2018-07-14 09:23:03 +09:00 · fc657410ff
commit fc657410ff
parent 5d13151cb9
20 changed files with 164 additions and 86 deletions
--- a/devtools/client/inspector/animation-old/test/head.js
+++ b/devtools/client/inspector/animation-old/test/head.js
@ -43,6 +43,7 @@ function enableAnimationFeatures() {
  return new Promise(resolve => {
    SpecialPowers.pushPrefEnv({"set": [
      ["dom.animations-api.core.enabled", true],
+      ["dom.animations-api.implicit-keyframes.enabled", true],
      ["dom.animations-api.timelines.enabled", true],
      ["layout.css.frames-timing.enabled", true],
    ]}, resolve);
--- a/devtools/client/inspector/animation/test/head.js
+++ b/devtools/client/inspector/animation/test/head.js
@ -61,6 +61,7 @@ const enableAnimationFeatures = function() {
  return new Promise(resolve => {
    SpecialPowers.pushPrefEnv({"set": [
      ["dom.animations-api.core.enabled", true],
+      ["dom.animations-api.implicit-keyframes.enabled", true],
      ["dom.animations-api.timelines.enabled", true],
      ["layout.css.frames-timing.enabled", true],
    ]}, resolve);
--- a/dom/animation/KeyframeUtils.cpp
+++ b/dom/animation/KeyframeUtils.cpp
@ -14,6 +14,7 @@
 #include "mozilla/ServoBindingTypes.h"
 #include "mozilla/ServoCSSParser.h"
 #include "mozilla/StyleAnimationValue.h"
+#include "mozilla/StaticPrefs.h"
 #include "mozilla/TimingParams.h"
 #include "mozilla/dom/BaseKeyframeTypesBinding.h" // For FastBaseKeyframe etc.
 #include "mozilla/dom/Element.h"
@ -22,12 +23,11 @@
 #include "mozilla/dom/Nullable.h"
 #include "jsapi.h" // For ForOfIterator etc.
 #include "nsClassHashtable.h"
-#include "nsContentUtils.h" // For GetContextForContent, and
-                            // AnimationsAPICoreEnabled
+#include "nsContentUtils.h" // For GetContextForContent
 #include "nsCSSPropertyIDSet.h"
 #include "nsCSSProps.h"
 #include "nsCSSPseudoElements.h" // For CSSPseudoElementType
-#include "nsDocument.h" // For nsDocument::IsWebAnimationsEnabled
+#include "nsDocument.h" // For nsDocument::AreWebAnimationsImplicitKeyframesEnabled
 #include "nsIScriptError.h"
 #include "nsTArray.h"
 #include <algorithm> // For std::stable_sort, std::min
@ -206,7 +206,7 @@ GetKeyframeListFromPropertyIndexedKeyframe(JSContext* aCx,
                                           ErrorResult& aRv);

 static bool
-RequiresAdditiveAnimation(const nsTArray<Keyframe>& aKeyframes,
+HasImplicitKeyframeValues(const nsTArray<Keyframe>& aKeyframes,
                          nsIDocument* aDocument);

 static void
@ -256,8 +256,8 @@ KeyframeUtils::GetKeyframesFromObject(JSContext* aCx,
    return keyframes;
  }

-  if (!nsDocument::IsWebAnimationsEnabled(aCx, nullptr) &&
-      RequiresAdditiveAnimation(keyframes, aDocument)) {
+  if (!nsDocument::AreWebAnimationsImplicitKeyframesEnabled(aCx, nullptr) &&
+      HasImplicitKeyframeValues(keyframes, aDocument)) {
    keyframes.Clear();
    aRv.Throw(NS_ERROR_DOM_ANIM_MISSING_PROPS_ERR);
  }
@ -781,7 +781,7 @@ AppendFinalSegment(AnimationProperty* aAnimationProperty,

 // Returns a newly created AnimationProperty if one was created to fill-in the
 // missing keyframe, nullptr otherwise (if we decided not to fill the keyframe
-// becase we don't support additive animation).
+// becase we don't support implicit keyframes).
 static AnimationProperty*
 HandleMissingInitialKeyframe(nsTArray<AnimationProperty>& aResult,
                             const KeyframeValueEntry& aEntry)
@ -789,10 +789,9 @@ HandleMissingInitialKeyframe(nsTArray<AnimationProperty>& aResult,
  MOZ_ASSERT(aEntry.mOffset != 0.0f,
             "The offset of the entry should not be 0.0");

-  // If the preference of the core Web Animations API is not enabled, don't fill
-  // in the missing keyframe since the missing keyframe requires support for
-  // additive animation which is guarded by this pref.
-  if (!nsContentUtils::AnimationsAPICoreEnabled()) {
+  // If the preference for implicit keyframes is not enabled, don't fill in the
+  // missing keyframe.
+  if (!StaticPrefs::dom_animations_api_implicit_keyframes_enabled()) {
    return nullptr;
  }

@ -812,10 +811,9 @@ HandleMissingFinalKeyframe(nsTArray<AnimationProperty>& aResult,
  MOZ_ASSERT(aEntry.mOffset != 1.0f,
             "The offset of the entry should not be 1.0");

-  // If the preference of the core Web Animations API is not enabled, don't fill
-  // in the missing keyframe since the missing keyframe requires support for
-  // additive animation which is guarded by this pref.
-  if (!nsContentUtils::AnimationsAPICoreEnabled()) {
+  // If the preference for implicit keyframes is not enabled, don't fill
+  // in the missing keyframe.
+  if (!StaticPrefs::dom_animations_api_implicit_keyframes_enabled()) {
    // If we have already appended a new entry for the property so we have to
    // remove it.
    if (aCurrentAnimationProperty) {
@ -1055,9 +1053,9 @@ GetKeyframeListFromPropertyIndexedKeyframe(JSContext* aCx,
    }

    // If we only have one value, we should animate from the underlying value
-    // using additive animation--however, we don't support additive animation
-    // when the core animation API pref is switched off.
-    if (!nsContentUtils::AnimationsAPICoreEnabled() && count == 1) {
+    // but not if the pref for supporting implicit keyframes is disabled.
+    if (!StaticPrefs::dom_animations_api_implicit_keyframes_enabled() &&
+        count == 1) {
      aRv.Throw(NS_ERROR_DOM_ANIM_MISSING_PROPS_ERR);
      return;
    }
@ -1216,17 +1214,15 @@ GetKeyframeListFromPropertyIndexedKeyframe(JSContext* aCx,
 /**
 * Returns true if the supplied set of keyframes has keyframe values for
 * any property for which it does not also supply a value for the 0% and 100%
- * offsets. In this case we are supposed to synthesize an additive zero value
- * but since we don't support additive animation yet we can't support this
- * case. We try to detect that here so we can throw an exception. The check is
- * not entirely accurate but should detect most common cases.
+ * offsets. The check is not entirely accurate but should detect most common
+ * cases.
 *
 * @param aKeyframes The set of keyframes to analyze.
 * @param aDocument The document to use when parsing keyframes so we can
 *   try to detect where we have an invalid value at 0%/100%.
 */
 static bool
-RequiresAdditiveAnimation(const nsTArray<Keyframe>& aKeyframes,
+HasImplicitKeyframeValues(const nsTArray<Keyframe>& aKeyframes,
                          nsIDocument* aDocument)
 {
  // We are looking to see if that every property referenced in |aKeyframes|
@ -1237,7 +1233,8 @@ RequiresAdditiveAnimation(const nsTArray<Keyframe>& aKeyframes,
  // a document which we might not always have at the point where we want to
  // perform this check.
  //
-  // This is only a temporary measure until we implement additive animation.
+  // This is only a temporary measure until we ship implicit keyframes and
+  // remove the corresponding pref.
  // So as long as this check catches most cases, and we don't do anything
  // horrible in one of the cases we can't detect, it should be sufficient.

--- a/dom/animation/test/chrome/test_animation_observers_sync.html
+++ b/dom/animation/test/chrome/test_animation_observers_sync.html
@ -1587,6 +1587,7 @@ SpecialPowers.pushPrefEnv(
  {
    set: [
      ["dom.animations-api.core.enabled", true],
+      ["dom.animations-api.implicit-keyframes.enabled", true],
      ["dom.animations-api.timelines.enabled", true],
    ],
  },
--- a/dom/animation/test/chrome/test_animation_properties.html
+++ b/dom/animation/test/chrome/test_animation_properties.html
@ -807,14 +807,21 @@ var gTests = [
 ];

 SpecialPowers.pushPrefEnv(
-  { set: [["dom.animations-api.core.enabled", true]] },
+  {
+    set: [
+      ["dom.animations-api.core.enabled", true],
+      ["dom.animations-api.implicit-keyframes.enabled", true],
+    ],
+  },
  function() {
    gTests.forEach(function(subtest) {
      test(function(t) {
        var div = addDiv(t);
        var animation = div.animate(subtest.frames, 100 * MS_PER_SEC);
-        assert_properties_equal(animation.effect.getProperties(),
-                                subtest.expected);
+        assert_properties_equal(
+          animation.effect.getProperties(),
+          subtest.expected
+        );
      }, subtest.desc);
    });

--- a/dom/animation/test/chrome/test_simulate_compute_values_failure.html
+++ b/dom/animation/test/chrome/test_simulate_compute_values_failure.html
@ -346,14 +346,21 @@ var gTests = [
 setup({explicit_done: true});

 SpecialPowers.pushPrefEnv(
-  { set: [["dom.animations-api.core.enabled", false]] },
+  {
+    set: [
+      ["dom.animations-api.core.enabled", false],
+      ["dom.animations-api.implicit-keyframes.enabled", false],
+    ],
+  },
  function() {
    gTests.forEach(function(subtest) {
      test(function(t) {
        var div = addDiv(t);
        var animation = div.animate(subtest.frames, 100 * MS_PER_SEC);
-        assert_properties_equal(animation.effect.getProperties(),
-                                subtest.expected);
+        assert_properties_equal(
+          animation.effect.getProperties(),
+          subtest.expected
+        );
      }, subtest.desc);
    });

--- a/dom/animation/test/crashtests/crashtests.list
+++ b/dom/animation/test/crashtests/crashtests.list
@ -15,17 +15,17 @@ pref(dom.animations-api.core.enabled,true) load 1291413-1.html
 pref(dom.animations-api.core.enabled,true) load 1291413-2.html
 pref(dom.animations-api.core.enabled,true) load 1304886-1.html
 pref(dom.animations-api.core.enabled,true) load 1309198-1.html
-pref(dom.animations-api.core.enabled,true) load 1322382-1.html
-pref(dom.animations-api.core.enabled,true) load 1322291-1.html
-pref(dom.animations-api.core.enabled,true) load 1322291-2.html
-pref(dom.animations-api.core.enabled,true) load 1323114-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1322382-1.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1322291-1.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1322291-2.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1323114-1.html
 pref(dom.animations-api.core.enabled,true) load 1323114-2.html
-pref(dom.animations-api.core.enabled,true) load 1323119-1.html
-pref(dom.animations-api.core.enabled,true) load 1324554-1.html
-pref(dom.animations-api.core.enabled,true) load 1325193-1.html
-pref(dom.animations-api.core.enabled,true) load 1330190-1.html
-pref(dom.animations-api.core.enabled,true) load 1330190-2.html
-pref(dom.animations-api.core.enabled,true) load 1330513-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1323119-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1324554-1.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1325193-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1330190-1.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1330190-2.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1330513-1.html
 pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.timelines.enabled,true) load 1333539-1.html
 pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.timelines.enabled,true) load 1333539-2.html
 load 1334582-1.html
@ -34,11 +34,11 @@ load 1334583-1.html
 pref(dom.animations-api.core.enabled,true) load 1335998-1.html
 pref(dom.animations-api.core.enabled,true) load 1343589-1.html
 pref(dom.animations-api.core.enabled,true) load 1359658-1.html
-pref(dom.animations-api.core.enabled,true) load 1373712-1.html
-pref(dom.animations-api.core.enabled,true) load 1379606-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1373712-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1379606-1.html
 load 1393605-1.html
 load 1400022-1.html
-pref(dom.animations-api.core.enabled,true) load 1401809.html
-pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.timelines.enabled,true) load 1411318-1.html
-load 1468294-1.html
-load 1467277-1.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1401809.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.timelines.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1411318-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1468294-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1467277-1.html
--- a/dom/animation/test/mochitest.ini
+++ b/dom/animation/test/mochitest.ini
@ -1,6 +1,7 @@
 [DEFAULT]
 prefs =
  dom.animations-api.core.enabled=true
+  dom.animations-api.implicit-keyframes.enabled=true
  dom.animations-api.timelines.enabled=true
 # Support files for chrome tests that we want to load over HTTP need
 # to go in here, not chrome.ini.
@ -9,6 +10,7 @@ support-files =
  mozilla/xhr_doc.html
  mozilla/file_deferred_start.html
  mozilla/file_disable_animations_api_core.html
+  mozilla/file_disable_animations_api_implicit_keyframes.html
  mozilla/file_disable_animations_api_timelines.html
  mozilla/file_discrete_animations.html
  mozilla/file_restyles.html
@ -40,6 +42,7 @@ skip-if = (verify && !debug && (os == 'mac'))
 [mozilla/test_deferred_start.html]
 skip-if = (toolkit == 'android' && debug) || (os == 'win' && bits == 64) # Bug 1363957
 [mozilla/test_disable_animations_api_core.html]
+[mozilla/test_disable_animations_api_implicit_keyframes.html]
 [mozilla/test_disable_animations_api_timelines.html]
 [mozilla/test_disabled_properties.html]
 [mozilla/test_discrete_animations.html]
--- a/dom/animation/test/mozilla/file_disable_animations_api_core.html
+++ b/dom/animation/test/mozilla/file_disable_animations_api_core.html
@ -25,38 +25,6 @@ test(function(t) {
 }, 'iterationComposite should not affect at all if the Web Animations API ' +
   'is not enabled');

-// Tests for cases we don't handle and should throw an exception for in case
-// the Web Animation API is disabled.
-var gTests = [
-  { desc: "single Keyframe with no offset",
-    keyframes: [{ left: "100px" }] },
-  { desc: "multiple Keyframes with missing 0% Keyframe",
-    keyframes: [{ left: "100px", offset: 0.25 },
-                { left: "200px", offset: 0.50 },
-                { left: "300px", offset: 1.00 }] },
-  { desc: "multiple Keyframes with missing 100% Keyframe",
-    keyframes: [{ left: "100px", offset: 0.00 },
-                { left: "200px", offset: 0.50 },
-                { left: "300px", offset: 0.75 }] },
-  { desc: "multiple Keyframes with missing properties on first Keyframe",
-    keyframes: [{ left: "100px", offset: 0.0 },
-                { left: "200px", top: "200px", offset: 0.5 },
-                { left: "300px", top: "300px", offset: 1.0 }] },
-  { desc: "multiple Keyframes with missing properties on last Keyframe",
-    keyframes: [{ left: "100px", top: "200px", offset: 0.0 },
-                { left: "200px", top: "200px", offset: 0.5 },
-                { left: "300px", offset: 1.0 }] },
-];
-
-gTests.forEach(function(subtest) {
-  test(function(t) {
-    var div = addDiv(t);
-    assert_throws("NotSupportedError", function() {
-      div.animate(subtest.keyframes, 100 * MS_PER_SEC);
-    });
-  }, "Element.animate() throws with " + subtest.desc);
-});
-
 done();
 </script>
 </body>
--- a/dom/animation/test/mozilla/file_disable_animations_api_implicit_keyframes.html
+++ b/dom/animation/test/mozilla/file_disable_animations_api_implicit_keyframes.html
@ -0,0 +1,48 @@
+<!doctype html>
+<meta charset=utf-8>
+<script src="../testcommon.js"></script>
+<body>
+<script>
+'use strict';
+
+// Tests for cases we should throw an exception for if implicit keyframes are
+// disabled.
+var gTests = [
+  { desc: "single Keyframe value",
+    keyframes: { left: "100px" } },
+  { desc: "single Keyframe with no offset",
+    keyframes: [{ left: "100px" }] },
+  { desc: "single Keyframe with 0% offset",
+    keyframes: [{ left: "100px", offset: 0 }] },
+  { desc: "single Keyframe with 100% offset",
+    keyframes: [{ left: "100px", offset: 1 }] },
+  { desc: "multiple Keyframes with missing 0% Keyframe",
+    keyframes: [{ left: "100px", offset: 0.25 },
+                { left: "200px", offset: 0.50 },
+                { left: "300px", offset: 1.00 }] },
+  { desc: "multiple Keyframes with missing 100% Keyframe",
+    keyframes: [{ left: "100px", offset: 0.00 },
+                { left: "200px", offset: 0.50 },
+                { left: "300px", offset: 0.75 }] },
+  { desc: "multiple Keyframes with missing properties on first Keyframe",
+    keyframes: [{ left: "100px", offset: 0.0 },
+                { left: "200px", top: "200px", offset: 0.5 },
+                { left: "300px", top: "300px", offset: 1.0 }] },
+  { desc: "multiple Keyframes with missing properties on last Keyframe",
+    keyframes: [{ left: "100px", top: "200px", offset: 0.0 },
+                { left: "200px", top: "200px", offset: 0.5 },
+                { left: "300px", offset: 1.0 }] },
+];
+
+gTests.forEach(function(subtest) {
+  test(function(t) {
+    var div = addDiv(t);
+    assert_throws("NotSupportedError", function() {
+      div.animate(subtest.keyframes, 100 * MS_PER_SEC);
+    });
+  }, "Element.animate() throws with " + subtest.desc);
+});
+
+done();
+</script>
+</body>
--- a/dom/animation/test/mozilla/test_disable_animations_api_implicit_keyframes.html
+++ b/dom/animation/test/mozilla/test_disable_animations_api_implicit_keyframes.html
@ -0,0 +1,14 @@
+<!doctype html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+'use strict';
+setup({explicit_done: true});
+SpecialPowers.pushPrefEnv(
+  { "set": [["dom.animations-api.implicit-keyframes.enabled", false]]},
+  function() {
+    window.open("file_disable_animations_api_implicit_keyframes.html");
+  });
+</script>
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@ -3307,6 +3307,17 @@ nsDocument::IsWebAnimationsEnabled(CallerType aCallerType)
         nsContentUtils::AnimationsAPICoreEnabled();
 }

+bool
+nsDocument::AreWebAnimationsImplicitKeyframesEnabled(JSContext* aCx,
+                                                     JSObject* /*unused*/
+)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  return nsContentUtils::IsSystemCaller(aCx) ||
+         StaticPrefs::dom_animations_api_implicit_keyframes_enabled();
+}
+
 bool
 nsDocument::AreWebAnimationsTimelinesEnabled(JSContext* aCx,
                                             JSObject* /*unused*/
--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@ -160,6 +160,8 @@ public:

  static bool IsWebAnimationsEnabled(JSContext* aCx, JSObject* aObject);
  static bool IsWebAnimationsEnabled(mozilla::dom::CallerType aCallerType);
+  static bool AreWebAnimationsImplicitKeyframesEnabled(JSContext* aCx,
+                                                       JSObject* aObject);
  static bool AreWebAnimationsTimelinesEnabled(JSContext* aCx,
                                               JSObject* aObject);

--- a/layout/base/crashtests/crashtests.list
+++ b/layout/base/crashtests/crashtests.list
@ -491,7 +491,7 @@ load 1308848-1.html
 load 1308848-2.html
 load 1338772-1.html
 load 1340571.html
-pref(dom.animations-api.core.enabled,true) load 1343139-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1343139-1.html
 asserts(0-1) load 1343606.html # bug 1343948
 load 1343937.html
 load 1352380.html
--- a/layout/style/crashtests/crashtests.list
+++ b/layout/style/crashtests/crashtests.list
@ -176,7 +176,7 @@ load 1321357-1.html
 load 1328535-1.html
 load 1331272.html
 HTTP load 1333001-1.html
-pref(dom.animations-api.core.enabled,true) load 1340344.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1340344.html
 load 1342316-1.html
 load 1344210.html
 load 1356601-1.html
@ -195,11 +195,11 @@ load 1381420-1.html
 load 1381682.html
 load 1382672.html
 load 1382710.html
-pref(dom.animations-api.core.enabled,true) load 1383493-1.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1383493-1.html
 load 1383001.html
 load 1383001-2.html
 load 1383319.html
-pref(dom.animations-api.core.enabled,true) load 1383589-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1383589-1.html
 load 1383975.html
 load border-image-visited-link.html
 load content-only-on-link-before.html
@ -219,14 +219,14 @@ load 1387499.html
 load 1388234.html
 load 1391577.html
 load 1393189.html
-load 1393580.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1393580.html
 load 1389645.html
 load 1390726.html
 load 1393791.html
 load 1384232.html
 load 1395725.html
 load 1396041.html
-load 1397363-1.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1397363-1.html
 load 1397439-1.html
 load 1395719.html
 load 1397091.html
@ -239,7 +239,7 @@ load 1400325.html
 load 1400926.html
 load 1400936-1.html
 load 1400936-2.html
-load 1401256.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1401256.html
 load 1401692.html
 load 1401706.html
 load 1401801.html
@ -275,7 +275,7 @@ load 1413361.html
 load 1413670.html
 pref(dom.webcomponents.shadowdom.enabled,true) load 1415353.html
 load 1418059.html
-test-pref(dom.animations-api.core.enabled,true) load 1418867.html
+test-pref(dom.animations-api.core.enabled,true) test-pref(dom.animations-api.implicit-keyframes.enabled,true) load 1418867.html
 pref(dom.webcomponents.shadowdom.enabled,true) load 1419554.html
 load 1426312.html
 load 1439793.html
--- a/layout/style/test/mochitest.ini
+++ b/layout/style/test/mochitest.ini
@ -1,6 +1,7 @@
 [DEFAULT]
 prefs =
  dom.animations-api.core.enabled=true
+  dom.animations-api.implicit-keyframes.enabled=true
  dom.animations-api.timelines.enabled=true
 support-files =
  animation_utils.js
--- a/modules/libpref/init/StaticPrefList.h
+++ b/modules/libpref/init/StaticPrefList.h
@ -91,6 +91,20 @@ VARCACHE_PREF(
 // DOM prefs
 //---------------------------------------------------------------------------

+// Is support for animations from the Web Animations API without 0%/100%
+// keyframes enabled?
+#ifdef RELEASE_OR_BETA
+# define PREF_VALUE false
+#else
+# define PREF_VALUE true
+#endif
+VARCACHE_PREF(
+  "dom.animations-api.implicit-keyframes.enabled",
+   dom_animations_api_implicit_keyframes_enabled,
+  bool, PREF_VALUE
+)
+#undef PREF_VALUE
+
 // Is support for timelines from the Web Animations API enabled?
 #ifdef RELEASE_OR_BETA
 # define PREF_VALUE false
--- a/testing/web-platform/meta/css/css-animations/dir.ini
+++ b/testing/web-platform/meta/css/css-animations/dir.ini
@ -1,2 +1,3 @@
 prefs: [dom.animations-api.core.enabled:true,
+        dom.animations-api.implicit-keyframes.enabled:true,
        dom.animations-api.timelines.enabled:true]
--- a/testing/web-platform/meta/css/css-transitions/dir.ini
+++ b/testing/web-platform/meta/css/css-transitions/dir.ini
@ -1,2 +1,3 @@
 prefs: [dom.animations-api.core.enabled:true,
+        dom.animations-api.implicit-keyframes.enabled:true,
        dom.animations-api.timelines.enabled:true]
--- a/testing/web-platform/meta/web-animations/dir.ini
+++ b/testing/web-platform/meta/web-animations/dir.ini
@ -1,3 +1,4 @@
 prefs: [dom.animations-api.core.enabled:true,
+        dom.animations-api.implicit-keyframes.enabled:true,
        dom.animations-api.timelines.enabled:true,
        layout.css.frames-timing.enabled:true]