Amp-ad test failure in old chrome #7917
Description
Chrome 45.0.2454 (Linux 0.0.0) Ad loader amp-ad falls back to Delayed Fetch if remote.html is used FAILED
TypeError: doc.head.append is not a function
at /tmp/2f06726ddd8d00d626276bbae795cee0.browserify:31169:20 <- /home/travis/build/ampproject/amphtml/extensions/amp-ad/0.1/test/test-amp-ad.js:143:19
.......
Chrome 45.0.2454 (Linux 0.0.0) Ad loader amp-embed falls back to Delayed Fetch if remote.html is used FAILED
TypeError: doc.head.append is not a function
at /tmp/2f06726ddd8d00d626276bbae795cee0.browserify:31169:20 <- /home/travis/build/ampproject/amphtml/extensions/amp-ad/0.1/test/test-amp-ad.js:143:19
From #7906