Fix issue #15689396: pre-installed DemoAPI tests fail...

...with a NPE on emulators running Google x86 API 19 image

Change-Id: Ib989127f48b0c02ec645b99827a9b775188684d8

core/java/android/app/Instrumentation.java

@@ -188,6 +188,9 @@ public class Instrumentation {
             endPerformanceSnapshot();
         }
         if (mPerfMetrics != null) {
+            if (results == null) {
+                results = new Bundle();
+            }
             results.putAll(mPerfMetrics);
         }
         if (mUiAutomation != null) {