[Android] Add test case for getUrl().

This patch is to add test case for getUrl().
Open a url, get the url on ui thread, compare it with the expected.
[Android] Post onRsourceLoadStarted on UI thread

The shouldInterceptRequest method which invokes onRsourceLoadStarted
is called from IO thread, and onResourceLoadStarted must be called
from UI thread, since XWalkResourceClient.onLoadStarted is called
by it in chain.

BUG=XWALK-1695
Merge pull request #1948 from xingnan/1695

[Android] Post onRsourceLoadStarted on UI thread
Merge pull request #1935 from wuhengzhi/getUrl_test

[Android] Add test case for getUrl().
[Runtime] Add dir and span support for widget

We can get right value for text items which have dir
propertie or span element in it.

This festure according to
http://www.w3.org/TR/widgets/#the-dir-attribute
http://www.w3.org/TR/widgets/#the-span-element-and-its-attributes