Fix presubmit errors in previous revision.

src/ia32/lithium-ia32.h

Index: src/ia32/lithium-ia32.h
diff --git a/src/ia32/lithium-ia32.h b/src/ia32/lithium-ia32.h
index 8450974eef5fb1231c891127b7ea885dde9b2bb4..647ba6aeae0acaa7352925e56d96b9b1f3ec583a 100644
--- a/src/ia32/lithium-ia32.h
+++ b/src/ia32/lithium-ia32.h
@@ -1998,7 +1998,7 @@ class LCheckNonSmi: public LTemplateInstruction<0, 1, 0> {
 
 class LAllocateObject: public LTemplateInstruction<1, 1, 0> {
  public:
-  LAllocateObject(LOperand* context) {
+  explicit LAllocateObject(LOperand* context) {
     inputs_[0] = context;
   }