Bindings: Add ScalarValueString support

Source/bindings/v8/V8Binding.cpp

Index: Source/bindings/v8/V8Binding.cpp
diff --git a/Source/bindings/v8/V8Binding.cpp b/Source/bindings/v8/V8Binding.cpp
index bef984e7af5aff1ac0aafda305d59436dbe6173d..3a30b2c108f71599bc4b6bed18695324104b87d5 100644
--- a/Source/bindings/v8/V8Binding.cpp
+++ b/Source/bindings/v8/V8Binding.cpp
@@ -499,6 +499,8 @@ String toByteString(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
         return String();
 
     // From the Web IDL spec: http://heycam.github.io/webidl/#es-ByteString
+    if (value.IsEmpty())
+        return String();
 
     // 1. Let x be ToString(v)
     TONATIVE_DEFAULT_EXCEPTIONSTATE(v8::Local<v8::String>, stringObject, value->ToString(), exceptionState, String());
@@ -517,6 +519,21 @@ String toByteString(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
     return x;
 }
 
+String toScalarValueString(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
+{
+    // From the Encoding standard (with a TODO to move to Web IDL):
+    // http://encoding.spec.whatwg.org/#type-scalarvaluestring
+    if (value.IsEmpty())
+        return String();
+    TONATIVE_DEFAULT_EXCEPTIONSTATE(v8::Local<v8::String>, stringObject, value->ToString(), exceptionState, String());
+
+    // ScalarValueString is identical to DOMString except that "convert a
+    // DOMString to a sequence of Unicode characters" is used subsequently
+    // when converting to an IDL value
+    String x = toCoreString(stringObject);
+    return x.toScalarValueString();
+}
+
 PassRefPtrWillBeRawPtr<XPathNSResolver> toXPathNSResolver(v8::Handle<v8::Value> value, v8::Isolate* isolate)
 {
     RefPtrWillBeRawPtr<XPathNSResolver> resolver = nullptr;