Bindings: Add ScalarValueString support

Source/core/testing/TypeConversions.idl

Index: Source/core/testing/TypeConversions.idl
diff --git a/Source/core/testing/TypeConversions.idl b/Source/core/testing/TypeConversions.idl
index 42474aad8fbbf45e8e54cacd3668e9b6c0e97bad..79e1fc6e3f9479fedb6add5dd465bd8f92edb200 100644
--- a/Source/core/testing/TypeConversions.idl
+++ b/Source/core/testing/TypeConversions.idl
@@ -53,4 +53,8 @@
     [ImplementedAs=testByteString, TreatReturnedNullStringAs=Undefined] ByteString getTestByteStringTreatReturnedNullStringAsUndefinedMethod();
     void setTestByteString(ByteString byteString);
     [ImplementedAs=setTestByteString] void setTestByteStringDefaultNull(optional ByteString byteString = null);
+
+    attribute ScalarValueString testScalarValueString;
+    void setTestScalarValueString(ScalarValueString scalarValueString);
+    [ImplementedAs=setTestScalarValueString] void setTestScalarValueStringDefaultNull(optional ScalarValueString scalarValueString = null);
 };