Deprecate fetching stylesheets with unsupported type

third_party/WebKit/Source/core/html/HTMLLinkElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp b/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
index 521b2ad779c311c6413ca9e8e061e94b3d777dfe..01508aac618e589b98a4a29c9b8474699b34d2dc 100644
--- a/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
@@ -51,6 +51,8 @@
 #include "core/loader/FrameLoaderClient.h"
 #include "core/loader/NetworkHintsInterface.h"
 #include "core/style/StyleInheritedData.h"
+#include "platform/ContentType.h"
+#include "platform/MIMETypeRegistry.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "public/platform/Platform.h"
 #include "wtf/StdLibExtras.h"
@@ -126,6 +128,12 @@ static LinkEventSender& linkLoadEventSender()
     return *sharedLoadEventSender;
 }
 
+static bool styleSheetTypeIsSupported(const String& type)
+{
+    String trimmedType = ContentType(type).type();
+    return trimmedType.isEmpty() || MIMETypeRegistry::isSupportedStyleSheetMIMEType(trimmedType);
+}
+
 void HTMLLinkElement::parseSizesAttribute(const AtomicString& value, Vector<IntSize>& iconSizes)
 {
     ASSERT(iconSizes.isEmpty());
@@ -713,6 +721,8 @@ void LinkStyle::process()
         return;
 
     if (m_disabledState != Disabled && m_owner->relAttribute().isStyleSheet() && shouldLoadResource() && builder.url().isValid()) {
+        if (!styleSheetTypeIsSupported(type))
+            UseCounter::countDeprecation(document(), UseCounter::NonCSSStyleSheetType);
 
         if (resource()) {
             removePendingSheet();