Removing TreatNullAs=NullString from SVGAngle.valueAsString and SVGLength.valueAsString attributes

Source/core/svg/SVGLength.idl

Index: Source/core/svg/SVGLength.idl
diff --git a/Source/core/svg/SVGLength.idl b/Source/core/svg/SVGLength.idl
index 52e2daafd47f846a72010b751e74a3cef7af6d58..9d424706f8de7d52c75138482cee9149c6c1c680 100644
--- a/Source/core/svg/SVGLength.idl
+++ b/Source/core/svg/SVGLength.idl
@@ -22,7 +22,6 @@
 
 // http://www.w3.org/TR/SVG2/types.html#InterfaceSVGLength
 
-// TODO(philipj): SVGLength should have constructors. crbug.com/366541
 [
     ImplementedAs=SVGLengthTearOff,
     SetWrapperReferenceTo(SVGElement contextElement),
@@ -47,8 +46,7 @@
     readonly attribute unsigned short unitType;
     [RaisesException] attribute float value;
     [RaisesException=Setter] attribute float valueInSpecifiedUnits;
-    // TODO(philipj): valueAsString should not have [TreatNullAs=NullString].
-    [TreatNullAs=NullString, RaisesException=Setter] attribute DOMString valueAsString;
+    [RaisesException=Setter] attribute DOMString valueAsString;
 
     [RaisesException] void newValueSpecifiedUnits(unsigned short unitType, float valueInSpecifiedUnits);
     [RaisesException] void convertToSpecifiedUnits(unsigned short unitType);