Rename RuntimeContext to XWalkBrowserContext

Since it's a browser context actually.
gyp: Cleanup Aura-related files and dependencies.

* Stop manually excluding _aura.cc files from the build, this is done
  automatically by Chromium's filename_rules.gypi. Ditto for files
  ending in _views.cc.

* Remove the dependency on the "aura_test_support" and "wm" targets. Not
  only does depending on a test target even when no tests are being
  bring a ton of additional dependencies, but neither targets seem to be
  needed at all, and were probably only needed in an earlier version of
  commit 336c03a ("runtime: Add aura-only native support").
DEPS.xwalk: Roll chromium-crosswalk (35b73bc -> abbaeb8).

abbaeb8 Merge pull request #214 from rakuco/revert-tizen-geolocation-changes
2d50c47 Revert Tizen changes to support changing the system location provider.

A proper implementation using those changes comes in the next commit.
[Tizen] Make the location provider implementation self-contained.

One of the problems with ld.bfd described in 7b83793 ("[Tizen] Start
using binutils-gold for linking Crosswalk again") was that when building
Crosswalk with -Dcomponent=shared_library ld.bfd would complain that
libcontent.so was missing symbol content::NewSystemLocationProvider().

Even though ld.gold links our binaries correctly, we are still having
problems _running_ them because the runtime linker cannot find an
implementation for that symbol (gyp causes lib/libcontent.so to be
passed after the .a archive containing the implementation in
content::NewSystemLocationProvider() from Crosswalk).

We can solve this the right way by making use of the infrastructure that
has been present in Chromium since at least M35 (!!): just override
ContentClientBrowser::OverrideSystemLocationProvider() and instantiate
Tizen's implementation there.
Merge pull request #2673 from rakuco/cleanup-aura-gyp-deps

gyp: Cleanup Aura-related files and dependencies.
Merge pull request #2671 from pozdnyakov/rename_RuntimeContext

Rename RuntimeContext to XWalkBrowserContext
Merge pull request #2674 from rakuco/tizen-implement-locationprovider-without-touching-content

[Tizen] Make the location provider implementation self-contained.
Roll DEPS.xwalk: chromium_crosswalk_rev (abbaeb8 -> ea46c0b)

ea46c0b Merge pull request #215 from pozdnyakov/XWALK_2789
17ac09e Fix GPU process crash
Bump version to 11.39.256.0
Merge branch 'master' of github.com-crosswalk:crosswalk-project/crosswalk
Merge pull request #2675 from pozdnyakov/roll_deps

Roll DEPS.xwalk: chromium_crosswalk_rev (abbaeb8 -> ea46c0b)
Bump version to 11.39.257.0
DEPS.xwalk: Roll v8-crosswalk (5b2efea -> f2bc708)

f2bc708 Merge pull request #62 from huningxin/fix-simd-reg-deoptimizer
34478f0 [SIMD.js] Refactor the simd128 registers in deoptimizer
883f9fd Merge pull request #60 from huningxin/fix-arm64
8299b0f [SIMD.js] Fix build failure on arm64 architecture
69921d6 Merge pull request #47 from vvavrychuk/simd-mips
75c28d9 [PATCH] fixed compilation v8 on mips
DEPS.xwalk: Roll v8-crosswalk (f2bc708 -> 825a59c)

825a59c Merge pull request #64 from halton/out-of-range-compare
b16ccb6 Merge pull request #63 from huningxin/m39-load-store-pr
8352127 [Backport] Fix clang++ warnings on -Wtautological-constant-out-of-range-compare
96bb068 [SIMD.js] Implement SIMD128 data load and store APIs
[Runtime] Add user href attribute check in widget element handler.

When parsing a widget config.xml file, runtime should make sure the author href
attribute is a valid URI, as it's required in W3C Widget spec. This patch will
fix this.

BUG=XWALK-2995
Merge pull request #2666 from huningxin/roll_v8

DEPS.xwalk: Roll v8-crosswalk (5b2efea -> f2bc708)
gyp: Cleanup dependency on re2.

- Stop always depending on it in xwalk_application_common.gypi, as it is
  only needed for Tizen.

- Remove dependency in xwalk_application.gypi now that the manifest
  handling files are in application/common/ and thus covered by
  xwalk_application_common.gypi.
Merge pull request #2676 from rakuco/gyp-cleanup-re2-dependency

gyp: Cleanup dependency on re2.
[Tizen] Add recognition of empty parameters in options of xwalk_backend

Empty path in -i option and incorrect pkgid in -r option were not
recognized. These parameters were unnecessary passed further to other
functions.

BUG=XWALK-3051
[Tizen] gyp: Move xmlsec detection to system.gyp.

This was the last remaining pkg-config call spread around random gyp
files. Move it to build/system.gyp with all the others and depend on the
"xmlsec" target in xwalk_application_common.gypi.