DevTools: [CodeMirror] improve indent autodetection

This patch improves indent autodetection for the following specific
usecase.
Consider a program indented with 2 spaces, but most of lines
resulted in indents of 4 and 8 spaces. At the moment, autodetection
will set indent to 4 spaces, which is wrong. The code and the test case
cover this situation.
This is not a made-up situation, I actually ran into it while editing
one of the CodeMirror's addons called "closebrackets".

BUG=
R=apavlov@chromium.org

Review URL: https://codereview.chromium.org/18284004

git-svn-id: svn://svn.chromium.org/blink/trunk@154227 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Introduce toHTMLMapElement

To avoid direct use of static_cast, this patch introduces toHTMLMapElement for code cleanup.

Review URL: https://chromiumcodereview.appspot.com/19191002

git-svn-id: svn://svn.chromium.org/blink/trunk@154228 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Unskip and rebaseline 'http/tests/security/sandboxed-iframe-form-top.html'

After contentshell, it doesn't appear that this test is leaking state into
the next test anymore. Yay!

R=jochen@chromium.org

Review URL: https://chromiumcodereview.appspot.com/19167003

git-svn-id: svn://svn.chromium.org/blink/trunk@154229 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add check against NPObject accesses after plugin NP_Shutdown().

TestNetscapePlugIn now creates a copy of the plugin script
object class on the heap, and overwrites it with garbage in
NP_Shutdown, to trap any attempts to call into plugin-side NPObject code after the plugin DLL might have been unloaded, independent of OS-specific DLL unload behaviour. 

BUG=152006

Review URL: https://chromiumcodereview.appspot.com/19067006

git-svn-id: svn://svn.chromium.org/blink/trunk@154230 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: [CodeMirror] CodeMirror v3.14.1 and new closebrackets plugin

This patch updates closebrackets plugin and codemirror core, which goes
with the plugin as a dependency. This version of codemirror core has
a speed-up patch with lazyfication of measurements to support long lines,
which might be found here:
https://github.com/aslushnikov/CodeMirror/tree/lazy-measure

BUG=

Review URL: https://chromiumcodereview.appspot.com/19168002

git-svn-id: svn://svn.chromium.org/blink/trunk@154231 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Rename the HolderContainer template parameter to CallbackInfo.

The templatized functions are called with PropertyCallbackInfo or
FunctionCallbackInfo. So it's clearer to call the template parameter
CallbackInfo than HolderContainer. (What does HolderContainer mean?)

BUG=

Review URL: https://chromiumcodereview.appspot.com/19204002

git-svn-id: svn://svn.chromium.org/blink/trunk@154232 bbb929c8-8fbe-4397-9dbb-9b2b20218538