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

third_party/WebKit/LayoutTests/inspector-protocol/emulation/device-emulation-initial-scale.js

+(async function(testRunner) {
+  let {page, session, dp} = await testRunner.startBlank(`
+    Tests that turning on device emulation with a non-1 device pixel ratio sets the
+    appropriate initial scale. Page scale is reflected by the innerWidth and
+    innerHeight properties. Since the layout width is set to 980 (in the viewport
+    meta tag), and the emulated viewport width is 490 px, the initial scale should
+    be 490/980 = 0.5. i.e. innerWidth=980 innerHeight=640.`);
+
+  var DeviceEmulator = await testRunner.loadScript('../resources/device-emulator.js');
+  var deviceEmulator = new DeviceEmulator(testRunner, session);
+  // 980px viewport loaded into a 490x320 screen should load at 0.5 scale.
+  await deviceEmulator.emulate(490, 320, 3);
+
+  var viewport = 'w=980';
+  testRunner.log(`Loading page with viewport=${viewport}`);
+  await session.navigate('../resources/device-emulation.html?' + viewport);
+
+  testRunner.log(await session.evaluate(`dumpMetrics(true)`));
+  testRunner.completeTest();
+})