Bug 1506298 - When tokenizing a string containing an escape sequence consisting of U+005C REVERSE SOLIDUS followed by a literal multi-unit code point, properly interpret the whole sequence as representing that multi-unit code point -- not as representing the first code unit of that sequence. #oops r=jorendorff

--HG--
extra : rebase_source : 19b8f7ee65ce05da38e9374d8716fb9979653369

js/src/frontend/TokenStream.cpp

@@ -3188,7 +3188,7 @@ TokenStreamSpecific<Unit, AnyCharsAccess>::getStringOrTemplateToken(char untilCh
                 // LineContinuation represents no code points, so don't append
                 // in this case.
                 if (codePoint != '\n') {
-                    if (!this->charBuffer.append(unit)) {
+                    if (!appendCodePointToCharBuffer(AssertedCast<char32_t>(codePoint))) {
                         return false;
                     }
                 }