Merge pull request #2743 from wuhengzhi/crosswalk-10

[Runtime] Add the initialization for |app_component_|.
[Runtime] Add the initialization for RuntimeFeature.

The struct about RuntimeFeature was not initialized with empty constructor,
assign the constructor with "default" to initialize the member variables.

CID=194651

Related to XWALK-2928.
(cherry picked from commit 266950eebfd5b264dc1e42d7106563a8b5c62137)