Revert of Replace NPObject usage in ppapi with gin

Revert of Replace NPObject usage in ppapi with gin (patchset #26 of https://codereview.chromium.org/459553003/)

Reason for revert:
Crash in telemetry tests http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_swarming/builds/6615

Original issue's description:
> Replace NPObject usage in ppapi with gin
> 
> This replaces usage of NPObject in pepper with gin-backed V8 objects. It is unfortunate that this CL is so large, but there isn't a nice way to have the old implementation and the new one side-by-side. 
> 
> There are 4 major parts to this CL:
> 1) Changing the HostVarTracker to track V8ObjectVars rather than NPObjectVars (host_var_tracker.cc).
> 2) Changing plugin elements (in plugin_object.cc) to be gin-backed objects. 
> 3) Changing postMessage bindings (message_channel.cc) be gin-backed objects.
> 4) Changing the implementation of PPB_Var_Deprecated (ppb_var_deprecated_impl.cc) to call directly into V8.
> 
> 
> BUG=351636
> 
> Committed: https://chromium.googlesource.com/chromium/src/+/21f446ae855d60cc896b40cb9a3249ed07f150b3

TBR=jochen@chromium.org,dmichael@chromium.org,kolczyk@opera.com
NOTREECHECKS=true
NOTRY=true
BUG=351636
Committed: https://crrev.com/93b2c74d78b7b9d9bcb8d45e7987e93a349772e7
Cr-Commit-Position: refs/heads/master@{#292322}

[raymes, 2014-08-28 04:49:44]

Created Revert of Replace NPObject usage in ppapi with gin

[raymes, 2014-08-28 04:50:02]

The CQ bit was checked by raymes@chromium.org

[commit-bot: I haz the power, 2014-08-28 04:51:20]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/raymes@chromium.org/512983004/1

[commit-bot: I haz the power, 2014-08-28 04:52:18]

Committed patchset #1 (id:1) as 43f5bc98dd4c5fefb73bc4f563bae54c4a479ebd

[commit-bot: I haz the power, 2014-09-10 02:57:34]

Patchset 1 (id:??) landed as
https://crrev.com/93b2c74d78b7b9d9bcb8d45e7987e93a349772e7
Cr-Commit-Position: refs/heads/master@{#292322}