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

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=150871

[eseidel, 2013-05-22 03:08:53]

lgtm

So long as we still get stacks! :)

[commit-bot: I haz the power, 2013-05-22 03:09:05]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/cevans@chromium.org/15275006/1

[Chris Evans, 2013-05-22 04:52:40]

On 2013/05/22 03:08:53, eseidel wrote:
> lgtm
> 
> So long as we still get stacks! :)

Yeah, GCC 4.6.3 on Ubuntu 12.04 uses a "ud2" instruction, leading to SIGILL --
definitely a condition we handle stack traces for. This is probably slightly
better than the current situation which is SIGSEGV and looks like a NULL crash.
The new way should look more like an assert.

If we preferred SIGTRAP, we could always switch to __asm__("int $3") in the
future.

[commit-bot: I haz the power, 2013-05-22 06:48:24]

Change committed as 150871