Fix ARM external array crankshaft bailout

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index 89ca1fd1feb64d86f04935a3c4d2b3d2da95799d..5d31473495a7dc3d9f124294be362ea9f4716f44 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -1827,6 +1827,7 @@ LInstruction* LChunkBuilder::DoLoadKeyedSpecializedArrayElement(
   // TODO(danno): Add support for other external array types.
   if (instr->array_type() != kExternalPixelArray) {
     Abort("unsupported load for external array type.");
+    return NULL;
   }
 
   ASSERT(instr->representation().IsInteger32());
@@ -1875,6 +1876,7 @@ LInstruction* LChunkBuilder::DoStoreKeyedSpecializedArrayElement(
   // TODO(danno): Add support for other external array types.
   if (instr->array_type() != kExternalPixelArray) {
     Abort("unsupported store for external array type.");
+    return NULL;
   }
 
   ASSERT(instr->value()->representation().IsInteger32());