Upgrade old chrome to 45

[aghassemi]

The final PR to get Master to green again.

• Saucelabs integration test have been stable for the past 20 or so rounds
• Only remaining failure was unit test failing on Chrome 37
• Don't use TextEncoder #5902, Fix test-iframe-createIframeWithMessageStub failures on older browsers #5895, Backward compatible way of stringifying Uint8Array #5881, Make SW test properly skip when Request == undefined #5876 include fixes so that unit tests can run on older versions of Chrome.
• Despite the fixes above, our code has diverged too much to be runnable on Chrome 37. Given 37 is just an arbitrary version and has become "too old", I am upgrading our old Chome to 45 (released more than a year ago)