The code in `AsmJsScanner::Next()` checks for both
end of input and parse error:

  if (token_ == kEndOfInput || token_ == kParseError) {
    return;
  }

but until now the code in the parsing loop only checked
for `kEndOfInput`, resulting in an infinite loop on
`kParseError`.

R=bradnelson@chromium.org, mstarzinger@chromium.org

Bug: chromium:771428
Change-Id: I9170f090503590b3b9b949a0d00ab4daef85bf66
Reviewed-on: https://chromium-review.googlesource.com/699994
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48290}