Fix content_browsertests failing frequently on swarming.

I have no idea why some builds pass now. Locally without this dll, it fails 100% of the time.

TBR=maruel

Review URL: https://codereview.chromium.org/435193004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287358 0039d316-1c4b-4281-b951-d872f2087c98

content/content_browsertests.isolate

@@ -80,7 +80,7 @@
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/content_shell.pak',
           '<(PRODUCT_DIR)/ffmpegsumo.dll',
-          '<(PRODUCT_DIR)/os_mesa.dll',
+          '<(PRODUCT_DIR)/osmesa.dll',
           '<(PRODUCT_DIR)/plugins/np_test_netscape_plugin.dll',
           '<(PRODUCT_DIR)/plugins/npapi_test_plugin.dll',
           '<(PRODUCT_DIR)/ppapi_tests.dll',