Implement Blink-side changes to enable V8 code caching.

Source/core/fetch/Resource.h

Index: Source/core/fetch/Resource.h
diff --git a/Source/core/fetch/Resource.h b/Source/core/fetch/Resource.h
index 635bcc5ab67d6f57ccb5a75114184cd8d3a9a0ab..f67f46a1702780a4dc4e2b7959aa5e7bd3a7d16a 100644
--- a/Source/core/fetch/Resource.h
+++ b/Source/core/fetch/Resource.h
@@ -194,6 +194,9 @@ public:
     // identifier that is used to distinguish data generated by the caller.
     void setCachedMetadata(unsigned dataTypeID, const char*, size_t);
 
+    // Reset existing metadata, to allow setting new data.
+    void clearCachedMetadata();
+
     // Returns cached metadata of the given type associated with this resource.
     CachedMetadata* cachedMetadata(unsigned dataTypeID) const;