Fix expectations for HostedAppTest.SubframeRedirectsToHostedApp

At some point the innerText of the test page gained a couple of newline
characters. This isn't important to the test so trim them out.
Also use EvalJs() instead of the deprecated ExecuteScript*().

Bug: 956047
Change-Id: I8a8a67dcef9838ba7350d17a8fb2b51ccb6bf043
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1585746
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Jay Harris <harrisjay@chromium.org>
Commit-Queue: Jay Harris <harrisjay@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654796}