Bug 124251 - Fix for some DOMStrings leaking when using -mail. r=dbaron, sr=jst

js/src/xpconnect/src/xpcstring.cpp

@@ -102,10 +102,9 @@ XPCReadableJSStringWrapper::GetSharedBufferHandle() const
         return sBufferHandle;
     }
 
-    XPCReadableJSStringWrapper * mutable_this =
-        NS_CONST_CAST(XPCReadableJSStringWrapper *, this);
-
     if (!mSharedBufferHandle) {
+        XPCReadableJSStringWrapper * mutable_this =
+            NS_CONST_CAST(XPCReadableJSStringWrapper *, this);
         PRUnichar *chars =
             NS_REINTERPRET_CAST(PRUnichar *, JS_GetStringChars(mStr));
 
@@ -119,10 +118,9 @@ XPCReadableJSStringWrapper::GetSharedBufferHandle() const
         }
 
         mutable_this->mSharedBufferHandle->RootString();
+        mutable_this->mSharedBufferHandle->AcquireReference();
     }
 
-    mutable_this->mSharedBufferHandle->AcquireReference();
-
     return mSharedBufferHandle;
 }