The default stack size of a background thread is 512KB on MacOSX. We default to
1MB stack checks when compiling JS code, so we need to increase this limit
to enable compilation of JS code onto background threads.

Corresponding Chromium CL is https://codereview.chromium.org/2640803002/

BUG=v8:5203

Review-Url: https://codereview.chromium.org/2653673007
Cr-Commit-Position: refs/heads/master@{#42650}