[DevTools] Migrate inspector-protocol/emulation tests to new harness

third_party/WebKit/LayoutTests/inspector-protocol/emulation/device-emulation-restore.js

+(async function(testRunner) {
+  let {page, session, dp} = await testRunner.startBlank('Tests that disabling device emulation restores back to original values.');
+
+  var DeviceEmulator = await testRunner.loadScript('../resources/device-emulator.js');
+  var deviceEmulator = new DeviceEmulator(testRunner, session);
+
+  var viewport = 'none';
+  await session.navigate('../resources/device-emulation.html?' + viewport);
+  var originalMetrics = await session.evaluate(`dumpMetrics(true)`);
+
+  await deviceEmulator.emulate(1200, 1000, 1);
+  viewport = 'w=320';
+  testRunner.log(`Loading page with viewport=${viewport}`);
+  await session.navigate('../resources/device-emulation.html?' + viewport);
+  testRunner.log(await session.evaluate(`dumpMetrics(true)`));
+
+  await deviceEmulator.clear();
+  viewport = 'none';
+  await session.navigate('../resources/device-emulation.html?' + viewport);
+  var metrics = await session.evaluate(`dumpMetrics(true)`);
+  if (metrics != originalMetrics)
+    testRunner.log('Original metrics not restored.\n==== Original ===\n' + originalMetrics + '\n==== Restored ====\n' + metrics);
+  else
+    testRunner.log('Original metrics restored correctly.');
+
+  testRunner.completeTest();
+})