Test for va_arg support on struct types (disabled on nested struct)

va_arg is not yet supported on nested struct types (see
https://code.google.com/p/nativeclient/issues/detail?id=3815)
Implement TTF_FontLineSkip
SDL_CreateRGBSurfaceFrom for surfaces with depth 32
add some slack to browser.test_sdl2_mouse
disable most websockify-using parts of sockets tests; #2700
fake cfgetospeed; #2926
Merge pull request #2921 from caiiiycuk/incoming

SDL_CreateRGBSurfaceFrom for surfaces with depth 32
Merge pull request #2924 from fhd/incoming

Implement TTF_FontLineSkip
Update simd.js for upstream changes.

The main change relevant to Emscripten here is that this includes the
fix for unaligned loads and stores.
[tracing] Add task tracing.
[tracing] Context data is used on the server side now.
[tracing] Add a way to track "associated storage size".

The docs cover this in more detail.
Fixed emscripten::val handle for special js values (undefined,null,true,false)
[embind docs] Reformat and cleanup whitespace.
val::equals, val::strictlyEquals
Rename simd.jd to ecmascript_simd.js

Since that's what the upstream name of this file is. Note that we are
still using a branch of upstream rather than plain upstream.
1.26.0
Implement _mm_loadu_ps and _mm_storeu_ps
Merge pull request #2929 from waywardmonkeys/embind-docs

[embind docs] Reformat and cleanup whitespace.
Merge pull request #2928 from waywardmonkeys/trace-extensions

Trace extensions