Version 3.31.12 (based on 7dcaa2652ac4642e006880aad6e32abb46e6a5b9)

Classes: Expand test to cover strict runtime behavior (issue 3330).

v8::String::Concat must not throw (Chromium issue 420240).

Fix disabling all break points from within the debug event callback (Chromium issue 432493).

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/candidates@{#25286}