Clean up the tests

[vivanishin]

• Use the existing testing facility (tools/run-tests.py).
• Get rid of the inlining hacks (we don't need them any more, and if we do, Flags: --nouse-inlining is a way to go).
• Use Flags: --llvm-filter=* where possible (or make it an option to run the test-runner with such a variant).
  • Remember to add --noturbo --noturbo-asm options for asm.js tests.
  • Test on regular v8 tests with --llvm-filter=*, see how many of them fail. We may want to switch to testing on those.
• The updated tests should have a much shorter running times (utilize %OptimizeFunctionOnNextCall(foo) and such).
• Don't throw away llv8-regtests for the time being. Keep it as a longer running and possibly more complete test suite.