Remove the strict-mode flag from store handlers. It's only relevant to the IC stub.

src/ic.h

Index: src/ic.h
diff --git a/src/ic.h b/src/ic.h
index 4a3e716db2893c80140c2fb1b416769fed861579..bfb73ac6a530772ad7bc02e9ee88a9a07c726b38 100644
--- a/src/ic.h
+++ b/src/ic.h
@@ -606,11 +606,7 @@ class StoreIC: public IC {
   }
 
   virtual Handle<Code> slow_stub() const {
-    if (strict_mode() == kStrictMode) {
-      return isolate()->builtins()->StoreIC_Slow_Strict();
-    } else {
-      return isolate()->builtins()->StoreIC_Slow();
-    }
+    return isolate()->builtins()->StoreIC_Slow();
   }
 
   virtual Handle<Code> pre_monomorphic_stub() {
@@ -723,11 +719,7 @@ class KeyedStoreIC: public StoreIC {
     }
   }
   virtual Handle<Code> slow_stub() const {
-    if (strict_mode() == kStrictMode) {
-      return isolate()->builtins()->KeyedStoreIC_Slow_Strict();
-    } else {
-      return isolate()->builtins()->KeyedStoreIC_Slow();
-    }
+    return isolate()->builtins()->KeyedStoreIC_Slow();
   }
   virtual Handle<Code> megamorphic_stub() {
     if (strict_mode() == kStrictMode) {