We have an internal limit of 50000 local variables per wasm function.
This limit is checked when decoding the function body. For asm.js, we
skip function body validation, since by construction the code we
generate is correct. This makes us fail unexpectedly when trying to
(lazily) compile an asm.js function with more than 50000 locals.
Hence, check this limit in the asm parser and bail out if it is
exceeded.

R=mstarzinger@chromium.org

Bug: chromium:775710
Change-Id: I89d2069e133fb0f84947d477ae1ac5eda85571aa
Reviewed-on: https://chromium-review.googlesource.com/732660Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48929}