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

third_party/WebKit/LayoutTests/inspector-protocol/resources/device-emulator.js

+(class DeviceEmulator {
+  constructor(testRunner, session) {
+    this._testRunner = testRunner;
+    this._session = session;
+  }
+
+  async emulate(width, height, deviceScaleFactor, insets) {
+    this._testRunner.log(`Emulating device: ${width}x${height}x${deviceScaleFactor}`);
+    var full = !!width && !!height && !!deviceScaleFactor;
+    var params = {
+      width,
+      height,
+      deviceScaleFactor,
+      mobile: true,
+      fitWindow: false,
+      scale: 1,
+      screenWidth: width,
+      screenHeight: height,
+      positionX: 0,
+      positionY: 0
+    };
+    if (insets) {
+      params.screenWidth += insets.left + insets.right;
+      params.positionX = insets.left;
+      params.screenHeight += insets.top + insets.bottom;
+      params.positionY = insets.top;
+    }
+    var response = await this._session.protocol.Emulation.setDeviceMetricsOverride(params);
+    if (response.error)
+      this._testRunner.log('Error: ' + response.error);
+  }
+
+  async clear() {
+    await this._session.protocol.Emulation.clearDeviceMetricsOverride();
+  }
+})