Remove prototype checks for leaf maps in optimized code.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 53f1b65755beaa3cbaa3ada0086830d60529bc27..6c6a2b7d01c23287c3e1b77ab536006ec2f4d29c 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -2567,6 +2567,13 @@ class HCheckPrototypeMaps: public HTemplateInstruction<0> {
     return hash;
   }
 
+  bool CanOmitPrototypeChecks() {
+    for (int i = 0; i < maps()->length(); i++) {
+      if (!maps()->at(i)->CanOmitPrototypeChecks()) return false;
+    }
+    return true;
+  }
+
  protected:
   virtual bool DataEquals(HValue* other) {
     HCheckPrototypeMaps* b = HCheckPrototypeMaps::cast(other);