Don't preload scripts with invalid type/language attributes

third_party/WebKit/Source/core/dom/ScriptLoader.cpp

Index: third_party/WebKit/Source/core/dom/ScriptLoader.cpp
diff --git a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
index a8337a8df390e92e0f5c4ad23955a52e56086473..fb2b72a35b07cb6faec43c3d1e1e9b2dfb454c92 100644
--- a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
+++ b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
@@ -163,19 +163,17 @@ void ScriptLoader::dispatchLoadEvent()
     setHaveFiredLoadEvent(true);
 }
 
-bool ScriptLoader::isScriptTypeSupported(LegacyTypeSupport supportLegacyTypes) const
+// static

[Yoav Weiss, 2016/06/25 08:08:16]

delete?

[Charlie Harrison, 2016/06/27 19:44:10]

Done.

+bool ScriptLoader::isValidScriptTypeAndLanguage(const String& type, const String& language, LegacyTypeSupport supportLegacyTypes)
 {
     // FIXME: isLegacySupportedJavaScriptLanguage() is not valid HTML5. It is used here to maintain backwards compatibility with existing layout tests. The specific violations are:
     // - Allowing type=javascript. type= should only support MIME types, such as text/javascript.
     // - Allowing a different set of languages for language= and type=. language= supports Javascript 1.1 and 1.4-1.6, but type= does not.
 
-    String type = client()->typeAttributeValue();
-    String language = client()->languageAttributeValue();
     if (type.isEmpty() && language.isEmpty())

[Yoav Weiss, 2016/06/25 08:08:16]

nit: we can move the language.isEmpty() check to the block below and save us a
condition check in some cases.

[Charlie Harrison, 2016/06/27 19:44:10]

Done.

         return true; // Assume text/javascript.
     if (type.isEmpty()) {
-        type = "text/" + language.lower();
-        if (MIMETypeRegistry::isSupportedJavaScriptMIMEType(type) || isLegacySupportedJavaScriptLanguage(language))
+        if (MIMETypeRegistry::isSupportedJavaScriptMIMEType(type + language.lower()) || isLegacySupportedJavaScriptLanguage(language))

[Yoav Weiss, 2016/06/25 08:08:16]

why "type + " here if type is empty? Did you mean it to be "text/"?

[Charlie Harrison, 2016/06/27 19:44:10]

Oops. Fixed.

             return true;
     } else if (RuntimeEnabledFeatures::moduleScriptsEnabled() && type == "module") {
         return true;
@@ -186,6 +184,11 @@ bool ScriptLoader::isScriptTypeSupported(LegacyTypeSupport supportLegacyTypes) c
     return false;
 }
 
+bool ScriptLoader::isScriptTypeSupported(LegacyTypeSupport supportLegacyTypes) const
+{
+    return isValidScriptTypeAndLanguage(client()->typeAttributeValue(), client()->languageAttributeValue(), supportLegacyTypes);
+}
+
 // http://dev.w3.org/html5/spec/Overview.html#prepare-a-script
 bool ScriptLoader::prepareScript(const TextPosition& scriptStartPosition, LegacyTypeSupport supportLegacyTypes)
 {