fix for bug 26938. r=tao a=ftang. fix \u encoding conversion so \n \r \t\ will be

convert to \n \r \t

intl/uconv/ucvlatin/nsUEscapeToUnicode.cpp

@@ -104,6 +104,17 @@ NS_IMETHODIMP nsUEscapeToUnicode::Convert(
           if(('u' == *srcPtr)  || ('U' == *srcPtr)) {
              mState++;
              mData=0;
+          } else if(('n' == *srcPtr)  || ('r' == *srcPtr) || ('t' == *srcPtr)) {
+             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;
+                goto error;
+             }
+             *destPtr++ = PRUnichar('\\');
+             *destPtr++ = (PRUnichar)*srcPtr;
           } else {
              mState =0;
              *destPtr++ = (PRUnichar)*srcPtr;

intl/uconv/ucvlatin/nsUnicodeToUEscape.cpp

@@ -101,10 +101,17 @@ NS_IMETHODIMP nsUnicodeToUEscape::Convert(const PRUnichar * aSrc, PRInt32 * aSrc
      {
        if( PRUnichar('\\') == *src)
        {
-           if((dest +2 ) >= destEnd)
-             goto error;
-           *dest++ = (char) '\\';
-           *dest++ = (char) '\\';
+           if(( PRUnichar('n') == *(1+src))||
+              ( PRUnichar('r') == *(1+src))||
+              ( PRUnichar('t') == *(1+src))) 
+           {
+             *dest++ = (char) *src;
+           } else {
+             if((dest +2 ) >= destEnd)
+               goto error;
+             *dest++ = (char) '\\';
+             *dest++ = (char) '\\';
+           }
        } else {
            *dest++ = (char) *src;
        }