Fix crash in gyp. TBR=brettw

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238489 0039d316-1c4b-4281-b951-d872f2087c98

build/gyp_chromium

@@ -73,7 +73,7 @@ def GetVarsStringForGN(supplemental_files):
         raise
       variables = file_data.get('variables')
       for v in variables:
-        vars_dict[v] = '"' + variables[v] + '"'
+        vars_dict[v] = '"' + str(variables[v]) + '"'
 
   env_string = os.environ.get('GYP_DEFINES', '')
   items = shlex.split(env_string)