Update nss_revision to 234862.

Includes the following CLs:

Update to NSS 3.15.3.
https://codereview.chromium.org/70673004/

R=agl@chromium.org
BUG=318442
TEST=none

Review URL: https://codereview.chromium.org/71503005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234990 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234991 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234990
SVN changes up to revision 234991
Fix frame detach message and lifetime issues for the mainframe RenderFrameImpl.

Previously, when RenderFrameImpl::frameDetach() was called on the mainframe, it would delete the RenderFrameImpl. The mainframe RFI is stored by RenderViewImpl in a scoped_ptr causing a double delete. This was not caught in testing because fast-path shutdown side-steps properly destroying the mainframe.

BUG=245126

Review URL: https://codereview.chromium.org/67313010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234992 0039d316-1c4b-4281-b951-d872f2087c98
Fix tabbing within iframes in the Files app.

This patch fixes the regression by not having underlying contents while showing a iframe. This problem is gone by adding the missing 'overlay-visible' attribute, what hides underlying contens while an iframe is visible, and therefore locks the tab within the iframe.

TEST=Try to delete an image from the photo viewer. Tab several times within the confirmation dialog.
BUG=315560

Review URL: https://codereview.chromium.org/69963002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234993 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234992
SVN changes up to revision 234993