Fix resetting of non-existing device

TRAC #18139
Signed-off-by: Daniel Koch
Author: Nicolas Capens

git-svn-id: https://angleproject.googlecode.com/svn/trunk@750 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/libEGL/Display.cpp b/src/libEGL/Display.cpp
index 84abbce..e031981 100644
--- a/src/libEGL/Display.cpp
+++ b/src/libEGL/Display.cpp
@@ -775,10 +775,12 @@
     {
         return FAILED(mDeviceEx->CheckDeviceState(NULL));
     }
-    else
+    else if(mDevice)
     {
         return FAILED(mDevice->TestCooperativeLevel());
     }
+
+    return false;   // No device yet, so no reset required
 }
 
 void Display::getMultiSampleSupport(D3DFORMAT format, bool *multiSampleArray)