Bug 1621849 - Add CSS Error for DisallowedImportRule r=emilio

- Add new CSS Error
- Add new test case for error
- Ensure that test cases use `replace()` and `replaceSync()`

Differential Revision: https://phabricator.services.mozilla.com/D69423

--HG--
extra : moz-landing-system : lando

dom/locales/en-US/chrome/layout/css.properties

@@ -39,6 +39,7 @@ PEMQNoMinMaxWithoutValue=Media features with min- or max- must have a value.
 PEMQExpectedFeatureValue=Found invalid value for media feature.
 PEExpectedNoneOrURL=Expected ‘none’ or URL but found ‘%1$S’.
 PEExpectedNoneOrURLOrFilterFunction=Expected ‘none’, URL, or filter function but found ‘%1$S’.
+PEDisallowedImportRule=@import rules are not yet valid in constructed stylesheets.
 
 TooLargeDashedRadius=Border radius is too large for ‘dashed’ style (the limit is 100000px). Rendering as solid.
 TooLargeDottedRadius=Border radius is too large for ‘dotted’ style (the limit is 100000px). Rendering as solid.

layout/style/test/test_css_parse_error_smoketest.html

@@ -10,6 +10,7 @@
 <style id="testbench"></style>
 <script>
   SpecialPowers.wrap(window).docShell.cssErrorReportingEnabled = true;
+  // Tests that apply to all types of style sheets
   var tests = [
     {
       css: "@unknown {}",
@@ -118,6 +119,14 @@
     },
   ];
 
+  // Tests that apply only to constructed style sheets
+  var constructedSheetTests = [
+    {
+      css: '@import url("sheet.css");',
+      error: "@import rules are not yet valid in constructed stylesheets."
+    }
+  ];
+
   function assertMessages(messages, action) {
     return new Promise(resolve => {
       SimpleTest.expectConsoleMessages(action, messages, resolve);
@@ -129,6 +138,12 @@
       let messages = [ { cssSelectors, errorMessage: error } ];
       await assertMessages(messages, () => { testbench.innerHTML = css });
       await assertMessages(messages, () => { new CSSStyleSheet().replaceSync(css) });
+      await assertMessages(messages, async () => { await new CSSStyleSheet().replace(css) });
+    }
+    for (let {css, cssSelectors = "", error} of constructedSheetTests) {
+      let messages = [ { cssSelectors, errorMessage: error } ];
+      await assertMessages(messages, () => { new CSSStyleSheet().replaceSync(css) });
+      await assertMessages(messages, async () => { await new CSSStyleSheet().replace(css) });
     }
   }
 

servo/components/style/stylesheets/rule_parser.rs

@@ -193,7 +193,7 @@ impl<'a, 'i> AtRuleParser<'i> for TopLevelRuleParser<'a> {
                 }
 
                 if let AllowImportRules::No = self.allow_import_rules {
-                    return Err(input.new_custom_error(StyleParseErrorKind::UnexpectedImportRule))
+                    return Err(input.new_custom_error(StyleParseErrorKind::DisallowedImportRule))
                 }
 
                 // FIXME(emilio): We should always be able to have a loader

servo/components/style_traits/lib.rs

@@ -137,6 +137,8 @@ pub enum StyleParseErrorKind<'i> {
     UnexpectedNamespaceRule,
     /// @import must be before any rule but @charset
     UnexpectedImportRule,
+    /// @import rules are disallowed in the parser.
+    DisallowedImportRule,
     /// Unexpected @charset rule encountered.
     UnexpectedCharsetRule,
     /// Unsupported @ rule
@@ -149,7 +151,6 @@ pub enum StyleParseErrorKind<'i> {
     ValueError(ValueParseErrorKind<'i>),
     /// An error was encountered while parsing a selector
     SelectorError(SelectorParseErrorKind<'i>),
-
     /// The property declaration was for an unknown property.
     UnknownProperty(CowRcStr<'i>),
     /// The property declaration was for a disabled experimental property.

servo/ports/geckolib/error_reporter.rs

@@ -298,6 +298,13 @@ impl<'a> ErrorHelpers<'a> for ContextualParseError<'a> {
                     ..
                 },
             ) => (cstr!("PEAtNSUnexpected"), Action::Nothing),
+            ContextualParseError::InvalidRule(
+                _,
+                ParseError {
+                    kind: ParseErrorKind::Custom(StyleParseErrorKind::DisallowedImportRule),
+                    ..
+                },
+            ) => (cstr!("PEDisallowedImportRule"), Action::Nothing),
             ContextualParseError::InvalidRule(
                 _,
                 ParseError {