Add a trap_on_abort flag

Add a trap_on_abort flag

By setting this flag assertions behind --debug-code will trigger a
breakpoint instead of a call into Abort. This eases debugging, as the
call site is less cluttered and the backtrace starts where it should.

BUG=
R=mstarzinger@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=16319

[Michael Starzinger, 2013-08-22 13:36:16]

LGTM with comments.

https://codereview.chromium.org/23352004/diff/2001/src/arm/macro-assembler-ar...
File src/arm/macro-assembler-arm.cc (right):

https://codereview.chromium.org/23352004/diff/2001/src/arm/macro-assembler-ar...
src/arm/macro-assembler-arm.cc:2852: DebugBreak();
You probably want to use "stop()" instead of "DebugBreak()" here, because
otherwise you are calling into the JavaScript debugger.

https://codereview.chromium.org/23352004/diff/2001/src/flag-definitions.h
File src/flag-definitions.h (right):

https://codereview.chromium.org/23352004/diff/2001/src/flag-definitions.h#new...
src/flag-definitions.h:267: DEFINE_bool(trap_on_abort, false,
nit: Should fit into one line. Also since this is only effective in debug mode,
it should be moved down into the "Debug only flags" section.

[oliv, 2013-08-26 11:23:45]

Committed patchset #2 manually as r16319 (presubmit successful).