Drop [IsIndex] attribute from CharacterData API

Source/core/dom/CharacterData.idl

Index: Source/core/dom/CharacterData.idl
diff --git a/Source/core/dom/CharacterData.idl b/Source/core/dom/CharacterData.idl
index eb9409f407a5e47f18a0426adf13334e3775ef0f..0999ab775d6752f96fa0bf6f449d5925a22d2f20 100644
--- a/Source/core/dom/CharacterData.idl
+++ b/Source/core/dom/CharacterData.idl
@@ -23,12 +23,12 @@ interface CharacterData : Node {
 
     readonly attribute unsigned long length;
 
-    [TreatReturnedNullStringAs=Null, RaisesException] DOMString substringData([IsIndex,Default=Undefined] optional unsigned long offset, [IsIndex,Default=Undefined] optional unsigned long length);
+    [TreatReturnedNullStringAs=Null, RaisesException] DOMString substringData([Default=Undefined] optional unsigned long offset, [IsIndex,Default=Undefined] optional unsigned long length);
 
     void appendData(DOMString data);
-    [RaisesException] void insertData([IsIndex] unsigned long offset, DOMString data);
-    [RaisesException] void deleteData([IsIndex] unsigned long offset, unsigned long length);
-    [RaisesException] void replaceData([IsIndex] unsigned long offset, unsigned long length, DOMString data);
+    [RaisesException] void insertData(unsigned long offset, DOMString data);
+    [RaisesException] void deleteData(unsigned long offset, unsigned long length);
+    [RaisesException] void replaceData(unsigned long offset, unsigned long length, DOMString data);
 };
 
 CharacterData implements ChildNode;