Fix broken path in GLES2 CTS.

AppendSwitch was casting all directories to lower case, causing the tests
to early-out and return as always passed even before they create the test
window.

BUG=408251

Review URL: https://codereview.chromium.org/500133005

Cr-Commit-Position: refs/heads/master@{#292413}

gpu/gles2_conform_support/gles2_conform_test.cc

@@ -64,7 +64,7 @@ bool RunGLES2ConformTest(const char* path) {
       "gles2_conform_test_windowless")));
 
   CommandLine cmdline(program);
-  cmdline.AppendSwitch(std::string("-run=") + path);
+  cmdline.AppendArg(std::string("-run=") + path);
 
   std::string output;
   bool success = base::GetAppOutput(cmdline, &output);