Bug 968857 - [SpecialPowers] Big files are truncated when loaded with loadChromeScript. r=ted, a=1.3+

With this patch, loadChromeScript now completely reads the input. This also
moves the loading code in its own function.

This also improves error reporting.
Bug 969365 - Do ShouldCheckAppCache with AppID and InBrowser in HttpChannelParent. r=jduell, a=1.3+
Bug 964974 - Part 1: Drop all active voice calls when powering off the radio. r=hsinyi, a=1.3+
Bug 964974 - Part 2: Marionette test for radio off during active voice call. r=hsinyi, a=1.3+
Bug 968542 - Prevent IPC blobs from entraining ContentParent objects. r=bent, a=1.3+