Revert of 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 6ae5e2cbb477047b898ac3631329920af767a1eb..a8337a8df390e92e0f5c4ad23955a52e56086473 100644
--- a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
+++ b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
@@ -121,7 +121,7 @@
     m_pendingScript = nullptr;
 }
 
-// Helper function. Must take a lowercase language as input.
+// Helper function
 static bool isLegacySupportedJavaScriptLanguage(const String& language)
 {
     // Mozilla 1.8 accepts javascript1.0 - javascript1.7, but WinIE 7 accepts only javascript1.1 - javascript1.3.
@@ -131,19 +131,24 @@
     // We want to accept all the values that either of these browsers accept, but not other values.
 
     // FIXME: This function is not HTML5 compliant. These belong in the MIME registry as "text/javascript<version>" entries.
-    DCHECK_EQ(language, language.lower());
-    return language == "javascript"
-        || language == "javascript1.0"
-        || language == "javascript1.1"
-        || language == "javascript1.2"
-        || language == "javascript1.3"
-        || language == "javascript1.4"
-        || language == "javascript1.5"
-        || language == "javascript1.6"
-        || language == "javascript1.7"
-        || language == "livescript"
-        || language == "ecmascript"
-        || language == "jscript";
+    typedef HashSet<String, CaseFoldingHash> LanguageSet;
+    DEFINE_STATIC_LOCAL(LanguageSet, languages, ());
+    if (languages.isEmpty()) {
+        languages.add("javascript");
+        languages.add("javascript1.0");
+        languages.add("javascript1.1");
+        languages.add("javascript1.2");
+        languages.add("javascript1.3");
+        languages.add("javascript1.4");
+        languages.add("javascript1.5");
+        languages.add("javascript1.6");
+        languages.add("javascript1.7");
+        languages.add("livescript");
+        languages.add("ecmascript");
+        languages.add("jscript");
+    }
+
+    return languages.contains(language);
 }
 
 void ScriptLoader::dispatchErrorEvent()
@@ -158,28 +163,27 @@
     setHaveFiredLoadEvent(true);
 }
 
-bool ScriptLoader::isValidScriptTypeAndLanguage(const String& type, const String& language, LegacyTypeSupport supportLegacyTypes)
+bool ScriptLoader::isScriptTypeSupported(LegacyTypeSupport supportLegacyTypes) const
 {
     // 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())
+        return true; // Assume text/javascript.
     if (type.isEmpty()) {
-        String lowerLanguage = language.lower();
-        return language.isEmpty() // assume text/javascript.
-            || MIMETypeRegistry::isSupportedJavaScriptMIMEType("text/" + lowerLanguage)
-            || isLegacySupportedJavaScriptLanguage(lowerLanguage);
+        type = "text/" + language.lower();
+        if (MIMETypeRegistry::isSupportedJavaScriptMIMEType(type) || isLegacySupportedJavaScriptLanguage(language))
+            return true;
     } else if (RuntimeEnabledFeatures::moduleScriptsEnabled() && type == "module") {
         return true;
-    } else if (MIMETypeRegistry::isSupportedJavaScriptMIMEType(type.stripWhiteSpace()) || (supportLegacyTypes == AllowLegacyTypeInTypeAttribute && isLegacySupportedJavaScriptLanguage(type.lower()))) {
+    } else if (MIMETypeRegistry::isSupportedJavaScriptMIMEType(type.stripWhiteSpace()) || (supportLegacyTypes == AllowLegacyTypeInTypeAttribute && isLegacySupportedJavaScriptLanguage(type))) {
         return true;
     }
 
     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
@@ -340,10 +344,9 @@
 
 void ScriptLoader::logScriptMimetype(ScriptResource* resource, LocalFrame* frame, String mimetype)
 {
-    String lowerMimetype = mimetype.lower();
-    bool text = lowerMimetype.startsWith("text/");
-    bool application = lowerMimetype.startsWith("application/");
-    bool expectedJs = MIMETypeRegistry::isSupportedJavaScriptMIMEType(lowerMimetype) || (text && isLegacySupportedJavaScriptLanguage(lowerMimetype.substring(5)));
+    bool text = mimetype.lower().startsWith("text/");
+    bool application = mimetype.lower().startsWith("application/");
+    bool expectedJs = MIMETypeRegistry::isSupportedJavaScriptMIMEType(mimetype) || (text && isLegacySupportedJavaScriptLanguage(mimetype.substring(5)));
     bool sameOrigin = m_element->document().getSecurityOrigin()->canRequest(m_resource->url());
     if (expectedJs) {
         return;