Make the strict-mode calling convention for contextual calls the default one.

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 090483bb38859804fc2abf60a739936963c365cf..bacdd2530fa08cf36f0d4ef7dbde7d71adc57c1b 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -1553,8 +1553,8 @@ class CallFunctionStub: public PlatformCodeStub {
   virtual void PrintName(StringStream* stream);
 
   // Minor key encoding in 32 bits with Bitfield <Type, shift, size>.
-  class FlagBits: public BitField<CallFunctionFlags, 0, 3> {};
-  class ArgcBits: public BitField<unsigned, 3, 32 - 3> {};
+  class FlagBits: public BitField<CallFunctionFlags, 0, 2> {};
+  class ArgcBits: public BitField<unsigned, 2, 32 - 2> {};
 
   Major MajorKey() { return CallFunction; }
   int MinorKey() {
@@ -1566,10 +1566,6 @@ class CallFunctionStub: public PlatformCodeStub {
     return (flags_ & RECEIVER_MIGHT_BE_IMPLICIT) != 0;
   }
 
-  bool ReceiverIsImplicit() {
-    return (flags_ & RECEIVER_IS_IMPLICIT) != 0;
-  }
-
   bool RecordCallTarget() {
     return (flags_ & RECORD_CALL_TARGET) != 0;
   }