Adding content_shell to the dependencies in the chromium_builder_tests target.

Some trybots bots, e.g. linux_clang, run webkit_tests, which use content_shell.
The bot only builds chromium_builder_tests. Since content_shell wasn't part of
this, webkit_tests didn't run an up-to-date content_shell binary on that bot,
which led to problems e.g. in try run
http://build.chromium.org/p/tryserver.chromium/builders/linux_clang/builds/117825/ on
cl https://codereview.chromium.org/17420005/.

Add content_shell to chromium_builder_tests to fix this.

BUG=237249
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/17397011

git-svn-id: http://src.chromium.org/svn/trunk/src/build@207486 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

all.gyp

@@ -227,6 +227,7 @@
             '../cloud_print/cloud_print.gyp:cloud_print_unittests',
             '../components/components.gyp:components_unittests',
             '../content/content.gyp:content_browsertests',
+            '../content/content.gyp:content_shell',
             '../content/content.gyp:content_unittests',
             '../device/device.gyp:device_unittests',
             '../gpu/gpu.gyp:gpu_unittests',