[Linux] Add NaCl support

Based on NaCl component work (http://crbug.com/244791) from upstream,
this commit is to add Native Client(aka NaCl) support.
It now can run examples from nacl sdk.
  $ cd <nacl_sdk_dir>/pepper_canary/example
  $ TOOLCHAIN=newlib make serve
  $ xwalk http://localhost:5103

BUG=XWALK-1338
[Android] Use intent actions to handle navigation according to MIME type.

Currently only "application/*" MIME type are handled by intent actions,
for other MIME types (text/*, video/*...) are still handled by XWalk.

BUG=XWALK-1560
[Android] Add the test case for evaluateJavascript.

This patch is to add the test case for evaluateJavascript.
Open a html file, set the title by evaluateJavascript, verify the
title with expected title.
[Android] Add the test case for addJavascriptInterface.

In this test case, we should use "@JavascriptInterface", it's from
"org.xwalk.core.JavascriptInterface", not
"android.webkit.JavascriptInterface".
In addition, if the target sdk version will be equal to or greater
than 17, "@JvascriptInterface" is required.

BUG=XWALK-1595
[Android] Fix the potential memory issue in XWalkPreferences

* Use WeakReference instead to make sure the key listener can be GC-ed
* Add unload internal method to remove the listener from the global list

BUG=https://crosswalk-project.org/jira/browse/XWALK-1613
[Runtime] Add i18n support for widget info

After locale was changed, we need to update widget info.
So that application widget api will get a localiation value.
[Tizen][Runtime] Update application information in DBus service when
updating.

When updating application, the information cached in DBus service should
be synced as well.

BUG=XWALK-1231
Revert "[Runtime Model] Packaging the XPK package generator in Linux & Windows"

We've never officially shipped any Windows or Linux archives, so this
target is not really serving any purpose.

This reverts commit 0b649e3b21882fe3b61afa8a4f46e6f54f51f144.
Stop checking for `tizen_mobile' in gyp wherever possible.

tizen_mobile has not been defined ever since we dropped support for
Tizen 2.x in 58841e7393074ea40e9a86bb55e8025256cf5af5, so the check has
been dead for a while.

Helps fix XWALK-1625.
Remove content_resource.pak from pak list.

The content_resources.pak only contains html/js/css files for chrome webui.
As the webui is not needed for xwalk, so just ignore it.
This can reduce size of xwalk.pak for about 150k

BUG=
Revert "[Android] Implement mixed resources to fix resource not found"

This reverts commit fbe4a5796cfa27a214a2ef2dc3e7cde3719d9c43.
[Android] Format the description, add links and correct typos.

Continue to refine the description of embedding API:
1. Use '<p>' to format the description.
2. Add links to Android API doc.
3. Correct some typos.

BUG=XWALK-1620
[Tizen][Runtime] Fix allow-navigation can not take effect in cross
origin page.

allow-navigation setting should take effect in all web app pages, but in
current implementation, it's only enforced for app local pages. This
patch will expand the scope.
[Android] Show launch screen dialog when no 'image' provided

Previously, when there is no 'image' provided, the launch screen dialog will not be displayed.
It should be displayed, because the backgrounds need to be displayed until the ready_when state.

BUG=XWALK-1635
[Runtime] Enable cookie for app and devtool schemes

Enable the content SQLite based cookie storage.
All installed applications will share the same database file, but the
access will be restricted by their application ID.

BUG=XWALK-1587
Merge pull request #1898 from yongsheng/refinedoc

[Android] Format the description, add links and correct typos.
Merge pull request #1894 from hmin/xwalk-preferences

[Android] Fix the potential memory issue in XWalkPreferences
Merge pull request #1904 from takethathe/allow-navigation

[Tizen][Runtime] Fix allow-navigation can not take effect in cross origin page.
Merge pull request #1801 from halton/nacl

[Linux] Add NaCl support
Merge pull request #1905 from kurli/launch-screen-show-bg

[Android] Show launch screen dialog when no 'image' provided