Make Geolocation internal test methods more resilient.

LayoutTests/fast/dom/Geolocation/script-tests/invalid-internals-arguments.js

+description("Verify that using invalid or detached documents on internal test methods does not crash.");
+
+// The internals object and these test methods aren't available in production
+// builds, but they are exposed to fuzzers.
+
+if (!window.testRunner || !window.internals)
+    debug('This test can not run without testRunner or internals');
+
+shouldThrow("internals.setGeolocationClientMock(null);");
+shouldThrow("internals.setGeolocationPosition(null, 1, 2, 3);");
+shouldThrow("internals.setGeolocationPermission(window.notThere, true);");
+shouldThrow("internals.setGeolocationPositionUnavailableError(null, 'not available');");
+shouldThrow("internals.numberOfPendingGeolocationPermissionRequests(null)");
+
+var ifr = document.getElementById("ifr");
+var iframe = ifr.contentWindow;
+ifr.remove();
+// Verify that detached documents do not crash.
+shouldBeUndefined("iframe.internals.setGeolocationClientMock(iframe.document)");
+shouldBeUndefined("iframe.internals.setGeolocationPosition(iframe.document, 1, 2, 3)");
+shouldBeUndefined("iframe.internals.setGeolocationPermission(iframe.document, true)");
+shouldBeUndefined("iframe.internals.setGeolocationPositionUnavailableError(iframe.document, 'not available')");
+shouldBe("iframe.internals.numberOfPendingGeolocationPermissionRequests(iframe.document)", "-1");