Implement suspend/resume for AudioContext

LayoutTests/webaudio/audiocontext-suspend-resume-expected.txt

+Test suspend/resume for an AudioContext
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS context.state is "paused"
+PASS context.suspend() did not throw exception.
+PASS context.suspend() did not throw exception.
+PASS p1 = context.resume() did not throw exception.
+PASS [object Object] is an instance of function Promise() { [native code] }
+PASS p2 = context.resume() did not throw exception.
+PASS [object Object] is an instance of function Promise() { [native code] }
+PASS Promises from resume are not equal.
+PASS context.state is "paused"
+PASS Context resumed correctly.
+PASS Context resumed correctly.
+PASS context.state is "released"
+PASS context.suspend() threw exception InvalidStateError: Failed to execute 'suspend' on 'AudioContext': cannot suspend an AudioContext that has been released.
+PASS resume() on a released context rejected as expected
+PASS successfullyParsed is true
+
+TEST COMPLETE
+