Revert "CSS: Drop the quirks-mode exception for CSS MIME types."

Source/core/fetch/CSSStyleSheetResource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 59 matching lines @@
     ASSERT(c->resourceClientType() == StyleSheetResourceClient::expectedType());
     // Resource::didAddClient() must be before setCSSStyleSheet(),
     // because setCSSStyleSheet() may cause scripts to be executed, which could destroy 'c' if it is an instance of HTMLLinkElement.
     // see the comment of HTMLLinkElement::setCSSStyleSheet.
     Resource::didAddClient(c);
 
     if (!isLoading())
         static_cast<StyleSheetResourceClient*>(c)->setCSSStyleSheet(m_resourceRequest.url(), m_response.url(), encoding(), this);
 }
 
-const String CSSStyleSheetResource::sheetText(bool* hasValidMIMEType) const
+const String CSSStyleSheetResource::sheetText(bool enforceMIMEType, bool* hasValidMIMEType) const
 {
     ASSERT(!isPurgeable());
 
-    if (!m_data || m_data->isEmpty() || !canUseSheet(hasValidMIMEType))
+    if (!m_data || m_data->isEmpty() || !canUseSheet(enforceMIMEType, hasValidMIMEType))
         return String();
 
     if (!m_decodedSheetText.isNull())
         return m_decodedSheetText;
 
     // Don't cache the decoded text, regenerating is cheap and it can use quite a bit of memory
     return decodedText();
 }
 
 const AtomicString CSSStyleSheetResource::mimeType() const
@@ skipping 23 matching lines @@
 {
     if (!m_parsedStyleSheetCache)
         return;
 
     m_parsedStyleSheetCache->removedFromMemoryCache();
     m_parsedStyleSheetCache.clear();
 
     setDecodedSize(0);
 }
 
-bool CSSStyleSheetResource::canUseSheet(bool* hasValidMIMEType) const
+bool CSSStyleSheetResource::canUseSheet(bool enforceMIMEType, bool* hasValidMIMEType) const
 {
     if (errorOccurred())
         return false;
 
+    if (!enforceMIMEType && !hasValidMIMEType)
+        return true;
+
     // This check exactly matches Firefox. Note that we grab the Content-Type
     // header directly because we want to see what the value is BEFORE content
     // sniffing. Firefox does this by setting a "type hint" on the channel.
     // This implementation should be observationally equivalent.
     //
     // This code defaults to allowing the stylesheet for non-HTTP protocols so
     // folks can use standards mode for local HTML documents.
     bool typeOK = mimeType().isEmpty() || equalIgnoringCase(mimeType(), "text/css") || equalIgnoringCase(mimeType(), "application/x-unknown-content-type");
     if (hasValidMIMEType)
         *hasValidMIMEType = typeOK;
+    if (!enforceMIMEType)
+        return true;
     return typeOK;
 }
 
 PassRefPtrWillBeRawPtr<StyleSheetContents> CSSStyleSheetResource::restoreParsedStyleSheet(const CSSParserContext& context)
 {
     if (!m_parsedStyleSheetCache)
         return nullptr;
     if (m_parsedStyleSheetCache->hasFailedOrCanceledSubresources()) {
         m_parsedStyleSheetCache->removedFromMemoryCache();
         m_parsedStyleSheetCache.clear();
@@ skipping 18 matching lines @@
 
     if (m_parsedStyleSheetCache)
         m_parsedStyleSheetCache->removedFromMemoryCache();
     m_parsedStyleSheetCache = sheet;
     m_parsedStyleSheetCache->addedToMemoryCache();
 
     setDecodedSize(m_parsedStyleSheetCache->estimatedSizeInBytes());
 }
 
 }