Migrate from page.waitFor in e2e tests

The next version of Puppeteer will deprecate `page.waitFor` (see
puppeteer/puppeteer#6268 for details) so this CL
gets us ahead of the curve by removing all the usages of it.

Change-Id: I0d8cf154b6ee561036df1cd999a64fac1b01cc6c
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2325220
Auto-Submit: Jack Franklin <jacktfranklin@chromium.org>
Reviewed-by: Paul Lewis <aerotwist@chromium.org>
Commit-Queue: Jack Franklin <jacktfranklin@chromium.org>

test/e2e/helpers/console-helpers.ts

@@ -135,7 +135,7 @@ export async function typeIntoConsole(frontend: puppeteer.Page, message: string)
   // The autocomplete element doesn't exist until the first autocomplete suggestion
   // is actaully given.
   const autocomplete = autocompleteHandle ? autocompleteHandle.asElement()! : null;
-  await frontend.waitFor(
+  await frontend.waitForFunction(
       (msg, ln, ac) => ln.textContent === msg && (!ac || ac.textContent === ''), undefined, message, line,
       autocomplete);
 

test/e2e/sources/script-in-multiple-workers_test.ts

@@ -117,7 +117,7 @@ describe('Multi-Workers', async function() {
           return;
         }
         await bpCheckbox.evaluate(n => (n as HTMLElement).click());
-        await frontend.waitFor('.cm-breakpoint-disabled');
+        await frontend.waitForSelector('.cm-breakpoint-disabled');
         // Add another breakpoint
         await addBreakpointForLine(frontend, 12);