Split out libplatform into a separate libary

Split out libplatform into a separate libary

Also remove the "use default platform" compile flag. Instead, the embedder
has to provide the platform.

Change all binaries to use the default platfrom from libplatform.

Unless --job-based-sweeping is passed, nothing uses the platform yet, so
nothing will break for embedders (yet).

BUG=none
R=jkummerow@chromium.org
LOG=y

Committed: https://code.google.com/p/v8/source/detail?r=22180

[Jakob Kummerow, 2014-07-02 07:37:52]

LGTM.

https://codereview.chromium.org/345903004/diff/1/samples/process.cc
File samples/process.cc (right):

https://codereview.chromium.org/345903004/diff/1/samples/process.cc#newcode650
samples/process.cc:650: v8::V8::InitializePlatform(platform);
Is it intentional that this platform is never shut down?

[jochen (gone - plz use gerrit), 2014-07-02 07:39:25]

https://codereview.chromium.org/345903004/diff/1/samples/process.cc
File samples/process.cc (right):

https://codereview.chromium.org/345903004/diff/1/samples/process.cc#newcode650
samples/process.cc:650: v8::V8::InitializePlatform(platform);
On 2014/07/02 07:37:52, Jakob wrote:
> Is it intentional that this platform is never shut down?

in this file, we also never dispose v8 (or the isolate or anything)

[jochen (gone - plz use gerrit), 2014-07-03 07:37:56]

Committed patchset #1 manually as r22180 (presubmit successful).

[tfarina, 2014-07-03 18:14:40]

https://codereview.chromium.org/345903004/diff/1/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/345903004/diff/1/BUILD.gn#newcode1067
BUILD.gn:1067: source_set("v8_libplatform") {
Does this needs visibility?

visibility = ":*"  # Only targets in this file can depend on this.

v8_libbase has this.

If it does not need, then my understanding is that external targets can depend
on this. Is that right?

https://codereview.chromium.org/345903004/diff/1/BUILD.gn#newcode1080
BUILD.gn:1080: configs += [ ":internal_config", ":features", ":toolchain" ]
does it need also these configs?

[jochen (gone - plz use gerrit), 2014-07-03 19:35:20]

https://codereview.chromium.org/345903004/diff/1/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/345903004/diff/1/BUILD.gn#newcode1067
BUILD.gn:1067: source_set("v8_libplatform") {
yes, external targets can depend on this

https://codereview.chromium.org/345903004/diff/1/BUILD.gn#newcode1080
BUILD.gn:1080: configs += [ ":internal_config", ":features", ":toolchain" ]
i've modified the configs a bit in a follow-up cl, but essentially, yes, it
does.