Migration to FPR6

[OlgaTPark]

Additionnal patches from Firefox ESR52 for FPR6 on Intel

This bug documents things took from https://github.com/classilla/tenfourfox/issues/478.

Not taking:

• [ ] M1433005 → Not in code;
• [ ] M1424709 → Apparently, the nano allocator doesn't apply to versions of Mac OS X prior to 10.9;
• [ ] M1398021 → LZ4 is also disabled in TenFourFox;

Wontfix:

• [ ] M1446365 → Which is a dupe for the patch applying to the libtremor part of M1446062 BUT the libtremor part of the patch isn't in TenFourFox (the remainder is in FPR7b1). libtremor is a integer-only replacement for libvorbis which lacks an encoder (it's unused in TFX and only used on ARM or Android — the two are mutually exclusive). Wontfixing it (so don't force MOZ_TREMOR to 1…);

Taking:

• [x] M1442504 → We support WebGL. This hides the (not so widespread) EXT_disjoint_timer_query extension under the webgl.enable-privileged-extensions about:config flag (the extension will still be visible by default for chrome contexts);
  • In fact, we have to adapt the patch because we don't have M1308057 which (among others) moves the EXT_disjoint_timer_query WebGL extension from « draft extensions » (having to be enabled via the webgl.enable-draft-extensions about:config flag) to « normal » ones.
    Also, the change for /dom/canvas/test/webgl-mochitest/mochitest.ini has to be applied to /dom/canvas/test/webgl-mochitest.ini.
• [x] M1388020 → This applies to a bit of IPC gfx which is maybe used in TenSixFox for plugins (at least?). The patch needs to be adapted to what it's possible to do here because the code changed since Firefox ESR 52;

Others:

Note for those who will be ever interested in what I do:
Because my fork is kinda old and I need to keep up, I won't be releasing a binary version of Ten*Fox FPR6 Intel. Don't worry, that's not meaning I'm giving up on this!