test(@angular-devkit/build-angular): update HMR test to support new chrome driver

(cherry picked from commit 38acdb7)

Author: alan-agius4

packages/angular_devkit/build_angular/src/dev-server/hmr_spec.ts

@@ -97,13 +97,13 @@ describe('Dev Server Builder HMR', () => {
               expect(logs).toContain(`[HMR] css reload %s ${url}styles.css`);
               expect(logs).toContain('[HMR] App is up to date.');
 
-              const pTag = await page.evaluate(() => {
+              const pTagColor = await page.evaluate(() => {
                 const el = document.querySelector('p');
 
-                return JSON.parse(JSON.stringify(getComputedStyle(el)));
+                return getComputedStyle(el).color;
               });
 
-              expect(pTag.color).toBe('rgb(255, 255, 0)');
+              expect(pTagColor).toBe('rgb(255, 255, 0)');
               break;
           }