Add WebKitUnitTestSupport::readFromFile and deprecate all PlatformFileHandle related methods

public/platform/WebUnitTestSupport.h

Index: public/platform/WebUnitTestSupport.h
diff --git a/public/platform/WebUnitTestSupport.h b/public/platform/WebUnitTestSupport.h
index 43dd0fe6ca323c1baf96486fc8d3658b783c2be1..a97a013b7d92ec216fd9df9dfb57c8f5b6a93286 100644
--- a/public/platform/WebUnitTestSupport.h
+++ b/public/platform/WebUnitTestSupport.h
@@ -27,6 +27,7 @@
 #define WebUnitTestSupport_h
 
 #include "WebCommon.h"
+#include "WebData.h"
 #include "WebString.h"
 
 namespace WebKit {
@@ -56,9 +57,10 @@ public:
 
     // Constructs a WebLayerTreeView set up with reasonable defaults for
     // testing.
-
     virtual WebLayerTreeView* createLayerTreeViewForTesting() { return 0; }
 
+    virtual WebData readFromFile(const WebString& path) { return WebData(); }
+
     // DEPRECATED, use the version above.
 #define HAVE_CREATELAYERTREEVIEWFORTESTING 1
     enum TestViewType {