Migration to FPR4

[OlgaTPark]

Additional patches from Firefox ESR52 for FPR4 on Intel

This bug documents things took from https://github.com/classilla/tenfourfox/issues/443.

Not taking:

• [x] M1408990 → Affected but this is corrected in FPR5 by https://github.com/classilla/tenfourfox/commit/cfdc685edba7b149a14fcc2ac496499e62ec0ad3#diff-a599edd6fdb81c244d2727dd626ad434;
• [ ] M1375146 → This seems to be an e10s-only bug;
• [ ] M1387799 → In code but unused (bug report says this bug was introduced in Firefox 50);
• [x] M1410106 → Fixed in FPR5 by https://github.com/classilla/tenfourfox/commit/8247519187dca976123e733ef15f333cc22b618c;
• [ ] M1261175 → Fixed in FPR6 with https://github.com/classilla/tenfourfox/commit/fd45dec140167dc590ea6b456877435408255cef;
• [ ] M1394265 → This bug was introduced by M1217290 in Firefox 57 (the type of WebGLContext::mGLMaxTextureUnits went from int32_t to uint32_t);

Taking:

• [x] TenFiveFox and TenSixFox are affected by M1406211 unless layers.offmainthreadcomposition.enabled is set to false (PPC TenFourFox and derivatives aren't affected because hardware acceleration is fully deactivated).

Deferred:

• [ ] M1416174 → Affected but the patch performs some medium refactoring;

Others:

• There's a few incompatibilities for Intel which are fixed with the following patches that aren't imported yet in this fork (those patches will be part of this fork when I'll update it to the corresponding FPR):
  • [x] https://github.com/classilla/tenfourfox/commit/dbe5530d53e0b24fd7ddaf42fae6dee2b07574b1 (part of TenFourFox FPR5);
  • [x] https://github.com/classilla/tenfourfox/commit/3c4213344c2d3ed83996ff3b7efa5558a2d6d804 (part of TenFourFox FPR5);
• [x] OTS requires the C++11 STL. You can either provide it or use the trick documented in the wiki

Note for those who will be ever interested in what I do:
e10s will always be deactivated due to incompatibilities with XUL and incomplete support in Firefox 45.
The patches https://github.com/classilla/tenfourfox/commit/615b887ce3cd70e85b1f20d7db4d396878cb617c and https://github.com/classilla/tenfourfox/commit/32df5d1470fa33e5edb7199ea9deaca073e460fd doesn't use conditional compilation for non-Mac OS X OSes. This is left unchanged because preprocessing is currently disabled for browser.js and tabbrowser.xml.