Fixed return value in error path -- result instead of false.

Found by VC++'s /analyze.

src\win8\test\ui_automation_client.cc(380) : warning C6216:
Compiler-inserted cast between semantically different integral types:
a Boolean type to HRESULT.

BUG=427616

Review URL: https://codereview.chromium.org/768513003

Cr-Commit-Position: refs/heads/master@{#306753}

win8/test/ui_automation_client.cc

@@ -377,7 +377,7 @@ HRESULT UIAutomationClient::Context::InvokeDesiredItem(
   var.Reset();
   if (FAILED(result)) {
     LOG(ERROR) << std::hex << result;
-    return false;
+    return result;
   }
 
   var.Set(item_name_.c_str());