When the incoming light source is invalid, don't generate any shadow

b/25417885

Change-Id: I4b87e35ca68091fd0409cb9fe9b9400af860a507
diff --git a/libs/hwui/ShadowTessellator.cpp b/libs/hwui/ShadowTessellator.cpp
index 1bca3e7..6c8665b 100644
--- a/libs/hwui/ShadowTessellator.cpp
+++ b/libs/hwui/ShadowTessellator.cpp
@@ -80,6 +80,11 @@
     ALOGD("light center %f %f %f %d",
             adjustedLightCenter.x, adjustedLightCenter.y, adjustedLightCenter.z, lightRadius);
 #endif
+    if (isnan(adjustedLightCenter.x)
+            || isnan(adjustedLightCenter.y)
+            || isnan(adjustedLightCenter.z)) {
+        return;
+    }
 
     // light position (because it's in local space) needs to compensate for receiver transform
     // TODO: should apply to light orientation, not just position