Revert 91859 - Porting ppapi_tests framework to postMessage.

Revert 91859 - Porting ppapi_tests framework to postMessage.

Some tests still rely on scripting, so we changed to using InstancePrivate (since scripting will disappear from Instance soon). Also use conditional compilation so that if compiled as untrusted with NaCl, the tests use Instance instead of InstancePrivate. This means that tests which rely on scripting aren't runnable in NaCl.

I also added a gyp option: pepper_scripting. The default is that scripting is on in this CL, but it will make it easy to turn it off in local builds. Soon we'll switch the default to no scripting, and soon after we can remove the option entirely.

BUG=82606
TEST=these tests

Review URL: http://codereview.chromium.org/7312008

TBR=dmichael@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=91866