[Android WebViewShell] Make WebViewLayoutTest runnable with test_runner.py
Make it possible to run the instrumentation tests in WebViewLayoutTest using
build/android/test_runner.py.
This patch adds an .isolate file, modifies the gyp target settings and uses
the standard paths for testing on the device. Also the apk now performs any
necessary copying (of js-test.js) itself, making it possible to run the
tests both locally and on the bots using the .isolate file.
BUG=497861
Review URL: https://codereview.chromium.org/
1215733002
Cr-Commit-Position: refs/heads/master@{#337040}