[XHR] remove now-unnecessary RaisesException attributes.

Source/core/xml/XMLHttpRequest.idl

Index: Source/core/xml/XMLHttpRequest.idl
diff --git a/Source/core/xml/XMLHttpRequest.idl b/Source/core/xml/XMLHttpRequest.idl
index f0a218f303810194fe8e2de5f2fb80d0cdfbefb1..af12ed5b466543d4bfc48187079afc86650b88d1 100644
--- a/Source/core/xml/XMLHttpRequest.idl
+++ b/Source/core/xml/XMLHttpRequest.idl
@@ -69,16 +69,16 @@ enum XMLHttpRequestResponseType {
     readonly attribute XMLHttpRequestUpload upload;
 
     // response
-    [TreatReturnedNullStringAs=Undefined, RaisesException] DOMString getAllResponseHeaders();
-    [TreatReturnedNullStringAs=Null, RaisesException] DOMString getResponseHeader(DOMString header);
+    [TreatReturnedNullStringAs=Undefined] DOMString getAllResponseHeaders();
+    [TreatReturnedNullStringAs=Null] DOMString getResponseHeader(DOMString header);
     [Custom=Getter, RaisesException=Getter] readonly attribute DOMString responseText; // The custom getter implements TreatReturnedNullStringAs=Null
     [RaisesException=Getter] readonly attribute Document responseXML;
 
     [RaisesException=Setter] attribute XMLHttpRequestResponseType responseType;
     [Custom=Getter, RaisesException=Getter] readonly attribute object response;
 
-    [RaisesException=Getter] readonly attribute unsigned short status;
-    [RaisesException=Getter] readonly attribute DOMString statusText;
+    readonly attribute unsigned short status;
+    readonly attribute DOMString statusText;
 
     // Extension
     void overrideMimeType(DOMString override);