Add missing check in Compiler Further AST traversals should not be run in case the expression complexity check failed and set success=false. Otherwise traversal can result in stack overflow. BUG=chromium:780545 TEST=WebGL conformance tests Change-Id: Icfde8c051038c691563e199a6d3a17b1e8e5ebf5 Reviewed-on: https://chromium-review.googlesource.com/750781 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>