Chromoting: Use different jscompile stamp files for v1 and v2 webapps.

Currently, both the v1 and the v2 webapps use the same stamp file for
their jscompile actions. The result of this is that the jscompile checks
will only be run for either v1 or v2, but not both.

This change derives the jscompile.stamp file from the target name so that
each webapp has its own stamp file.

BUG=

Review URL: https://codereview.chromium.org/474383002

Cr-Commit-Position: refs/heads/master@{#290137}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290137 0039d316-1c4b-4281-b951-d872f2087c98

remoting/remoting_webapp.gypi

@@ -21,7 +21,7 @@
   'conditions': [
     ['run_jscompile != 0', {
       'variables': {
-        'success_stamp': '<(PRODUCT_DIR)/remoting_webapp_jscompile.stamp',
+        'success_stamp': '<(PRODUCT_DIR)/<(_target_name)_jscompile.stamp',
       },
       'actions': [
         {