Use __builtin_trap() on GCC too.
Use __builtin_trap() on GCC too.

This saves 174608 bytes(!) in a Release DumpRenderTree on Linux x64.
Yeah, I checked it twice.

The old byte sequence is at least 4 bytes (plus a possible register trash which
may incur extra code bytes). The new sequence is a single byte.

R=eseidel@chromium.org

Review URL: https://chromiumcodereview.appspot.com/15275006

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@150871 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs