"NULL !=" = NULL

R=reed@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/544233002
diff --git a/tools/skpdiff/skpdiff_main.cpp b/tools/skpdiff/skpdiff_main.cpp
index 9c1f37f..c01767e 100644
--- a/tools/skpdiff/skpdiff_main.cpp
+++ b/tools/skpdiff/skpdiff_main.cpp
@@ -134,7 +134,7 @@
 
     // Figure which differs the user chose, and optionally print them if the user requests it
     SkTDArray<SkImageDiffer*> chosenDiffers;
-    for (int differIndex = 0; NULL != gDiffers[differIndex]; differIndex++) {
+    for (int differIndex = 0; gDiffers[differIndex]; differIndex++) {
         SkImageDiffer* differ = gDiffers[differIndex];
         if (FLAGS_list) {
             SkDebugf("    %s", differ->getName());