[webcrypto] Implement structured clone of keys (blink-side).

LayoutTests/fast/storage/resources/serialized-script-value.js

-var kSerializedScriptValueVersion = 4;
+var kSerializedScriptValueVersion = 5;
 
 function forVersion(version, values) {
     var versionTag = 0xff;
     var versionPrefix = [ (version << 8) | versionTag ];
 
     return versionPrefix.concat(values)
 }
 
 function expectBufferValue(bytesPerElement, expectedValues, buffer) {
     expectedBufferValues = expectedValues;
@@ skipping 146 matching lines @@
     self.fileObj1 = new File(['The', ' contents'], 'testfile.txt', {type: 'text/plain', lastModified: 0});
     self.fileObj2 = internals.deserializeBuffer(internals.serializeObject(self.fileObj1));
     shouldBeTrue("areValuesIdentical(fileObj1, fileObj2)");
     self.dictionaryWithFile1 = {file: fileObj1, string: 'stringValue'};
     self.dictionaryWithFile2 = internals.deserializeBuffer(internals.serializeObject(dictionaryWithFile1));
     shouldBeTrue("areValuesIdentical(dictionaryWithFile1, dictionaryWithFile2)");
 
     // Read and compare actual contents.
     checkIfSameContent(self.fileObj1, self.fileObj2, finishJSTest);
 }