diff --git a/browser/base/content/test/performance/browser.ini b/browser/base/content/test/performance/browser.ini
index 401fdc92a4bb..37c160f08374 100644
--- a/browser/base/content/test/performance/browser.ini
+++ b/browser/base/content/test/performance/browser.ini
@@ -15,10 +15,11 @@ support-files =
 [browser_appmenu_reflows.js]
 skip-if = asan || debug # Bug 1382809, bug 1369959
 [browser_startup.js]
+skip-if = devedition # We ship startupRecorder.js on DevEdition, but this test still fails with it
 [browser_startup_content.js]
 skip-if = !e10s
 [browser_startup_flicker.js]
-run-if = debug || nightly_build # Requires startuprecorder.js, which is only available on debug & trunk
+run-if = debug || devedition || nightly_build # Requires startupRecorder.js, which isn't shipped everywhere by default
 [browser_tabclose_grow_reflows.js]
 [browser_tabclose_reflows.js]
 [browser_tabopen_reflows.js]
diff --git a/browser/installer/package-manifest.in b/browser/installer/package-manifest.in
index 644cb0e1b8ea..93ecef3c817f 100644
--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -555,7 +555,7 @@
 @RESPATH@/components/TestInterfaceJSMaplike.js
 #endif
 
-#if defined(MOZ_DEBUG) || defined(NIGHTLY_BUILD)
+#if defined(MOZ_DEBUG) || defined(MOZ_DEV_EDITION) || defined(NIGHTLY_BUILD)
 @RESPATH@/browser/components/testComponents.manifest
 @RESPATH@/browser/components/startupRecorder.js
 #endif
diff --git a/build/docs/mozinfo.rst b/build/docs/mozinfo.rst
index dd05d0a70f64..e7d2ed6749f2 100644
--- a/build/docs/mozinfo.rst
+++ b/build/docs/mozinfo.rst
@@ -86,6 +86,13 @@ debug
 
    Always defined.
 
+devedition
+   Whether this is a devedition build.
+
+   Values are ``true`` and ``false``.
+
+   Always defined.
+
 healthreport
    Whether the Health Report feature is enabled.
 
diff --git a/dom/media/ChannelMediaDecoder.cpp b/dom/media/ChannelMediaDecoder.cpp
index 366a63d6431b..d01a86199e5f 100644
--- a/dom/media/ChannelMediaDecoder.cpp
+++ b/dom/media/ChannelMediaDecoder.cpp
@@ -337,6 +337,7 @@ ChannelMediaDecoder::NotifyDownloadEnded(nsresult aStatus)
       });
     nsresult rv = GetStateMachine()->OwnerThread()->Dispatch(r.forget());
     MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+    Unused << rv;
     owner->DownloadSuspended();
     // NotifySuspendedStatusChanged will tell the element that download
     // has been suspended "by the cache", which is true since we never
@@ -403,6 +404,7 @@ ChannelMediaDecoder::DurationChanged()
     });
   nsresult rv = GetStateMachine()->OwnerThread()->Dispatch(r.forget());
   MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  Unused << rv;
 }
 
 void
diff --git a/dom/media/CubebUtils.cpp b/dom/media/CubebUtils.cpp
index 051546105720..26f158a0c727 100644
--- a/dom/media/CubebUtils.cpp
+++ b/dom/media/CubebUtils.cpp
@@ -449,12 +449,14 @@ cubeb* GetCubebContextUnlocked()
   }
 
 #ifdef MOZ_CUBEB_REMOTING
-  if (XRE_IsParentProcess()) {
-    // TODO: Don't use audio IPC when within the same process.
-    MOZ_ASSERT(!sIPCConnection.IsValid());
-    sIPCConnection = CreateAudioIPCConnection();
-  } else {
-    MOZ_DIAGNOSTIC_ASSERT(sIPCConnection.IsValid());
+  if (sCubebSandbox) {
+    if (XRE_IsParentProcess()) {
+      // TODO: Don't use audio IPC when within the same process.
+      MOZ_ASSERT(!sIPCConnection.IsValid());
+      sIPCConnection = CreateAudioIPCConnection();
+    } else {
+      MOZ_DIAGNOSTIC_ASSERT(sIPCConnection.IsValid());
+    }
   }
 
   MOZ_LOG(gCubebLog, LogLevel::Info, ("%s: %s", PREF_CUBEB_SANDBOX, sCubebSandbox ? "true" : "false"));
@@ -556,7 +558,7 @@ void InitLibrary()
     NS_NewRunnableFunction("CubebUtils::InitLibrary", &InitBrandName));
 #endif
 #ifdef MOZ_CUBEB_REMOTING
-  if (XRE_IsContentProcess()) {
+  if (sCubebSandbox && XRE_IsContentProcess()) {
     AbstractThread::MainThread()->Dispatch(
       NS_NewRunnableFunction("CubebUtils::InitLibrary", &InitAudioIPCConnection));
   }
diff --git a/js/src/tests/non262/extensions/regress-346773.js b/js/src/tests/non262/extensions/regress-346773.js
index fe0198720655..024da5c72091 100644
--- a/js/src/tests/non262/extensions/regress-346773.js
+++ b/js/src/tests/non262/extensions/regress-346773.js
@@ -5,7 +5,7 @@
 
 //-----------------------------------------------------------------------------
 var BUGNUMBER = 346773;
-var summary = 'Do not crash compiling with misplaced brances in function';
+var summary = 'Do not crash compiling with misplaced branches in function';
 var actual = 'No Crash';
 var expect = 'No Crash';
 
diff --git a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
index 302e77329939..33834db00a21 100644
--- a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
+++ b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
@@ -578,6 +578,7 @@ public:
         self->InternalProcessAudioChunk(aRate, aChunk, aEnabled);
       }));
     MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+    Unused << rv;
   }
 
 protected:
diff --git a/python/mozbuild/mozbuild/mozinfo.py b/python/mozbuild/mozbuild/mozinfo.py
index 205a6c743de9..7e7ad1b2a8f2 100755
--- a/python/mozbuild/mozbuild/mozinfo.py
+++ b/python/mozbuild/mozbuild/mozinfo.py
@@ -77,6 +77,7 @@ def build_dict(config, env=os.environ):
     d['debug'] = substs.get('MOZ_DEBUG') == '1'
     d['nightly_build'] = substs.get('NIGHTLY_BUILD') == '1'
     d['release_or_beta'] = substs.get('RELEASE_OR_BETA') == '1'
+    d['devedition'] = substs.get('MOZ_DEV_EDITION') == '1'
     d['pgo'] = substs.get('MOZ_PGO') == '1'
     d['crashreporter'] = bool(substs.get('MOZ_CRASHREPORTER'))
     d['datareporting'] = bool(substs.get('MOZ_DATA_REPORTING'))
diff --git a/testing/web-platform/meta/css-timing/__dir__.ini b/testing/web-platform/meta/css/css-timing/__dir__.ini
similarity index 100%
rename from testing/web-platform/meta/css-timing/__dir__.ini
rename to testing/web-platform/meta/css/css-timing/__dir__.ini