fix bug 21418. Make '\n' output '\n' instead of 'n'. r=jbetak

intl/uconv/ucvlatin/nsUEscapeToUnicode.cpp

@@ -105,8 +105,17 @@ NS_IMETHODIMP nsUEscapeToUnicode::Convert(
              mState++;
              mData=0;
           } else {
-             mState =0;
+             if((destPtr+2) >= destEnd) {
+                   // notice the data in mBuffer is stored in reversed order
+                   mBufferLen = 2;
+                   mBuffer[1] = (PRUnichar) '\\';
+                   mBuffer[0] = (PRUnichar)*srcPtr;
+                   mState=0;
+                   goto error;
+             }
+             *destPtr++ = (PRUnichar) '\\';
              *destPtr++ = (PRUnichar)*srcPtr;
+             mState=0;
           }
           break;
         case 2:  // got \u