Bug 1386404 - Enable access to the entire chrome dir from content. r=jld

This may be required if people have @import in their userContent.css, and
in any case our tests check for this.

MozReview-Commit-ID: 8uJcWiC2rli

--HG--
extra : rebase_source : 38bd2a2ffc593bf94b3c16f0c755d169d5998f7f

security/sandbox/linux/broker/SandboxBrokerPolicyFactory.cpp

@@ -451,13 +451,10 @@ SandboxBrokerPolicyFactory::GetContentPolicy(int aPid, bool aFileProcess)
       if (NS_SUCCEEDED(rv)) {
         rv = workDir->AppendNative(NS_LITERAL_CSTRING("chrome"));
         if (NS_SUCCEEDED(rv)) {
-          rv = workDir->AppendNative(NS_LITERAL_CSTRING("userContent.css"));
+          nsAutoCString tmpPath;
+          rv = workDir->GetNativePath(tmpPath);
           if (NS_SUCCEEDED(rv)) {
-            nsAutoCString tmpPath;
-            rv = workDir->GetNativePath(tmpPath);
-            if (NS_SUCCEEDED(rv)) {
-              policy->AddPath(rdonly, tmpPath.get());
-            }
+            policy->AddDir(rdonly, tmpPath.get());
           }
         }
       }