Revert of Thread maybe-assigned through the bytecodes.

test/cctest/interpreter/bytecode_expectations/Delete.golden

 #
 # Autogenerated by generate-bytecode-expectations.
 #
 
 ---
 wrap: yes
 
 ---
 snippet: "
   var a = {x:13, y:14}; return delete a.x;
@@ skipping 89 matching lines @@
 parameter count: 1
 bytecode array length: 27
 bytecodes: [
                 B(CreateFunctionContext), U8(1),
                 B(PushContext), R(0),
   /*   30 E> */ B(StackCheck),
   /*   56 S> */ B(CreateObjectLiteral), U8(0), U8(2), U8(1), R(1),
                 B(Ldar), R(1),
   /*   56 E> */ B(StaCurrentContextSlot), U8(4),
   /*   64 S> */ B(CreateClosure), U8(1), U8(3), U8(2),
-  /*   93 S> */ B(LdaImmutableCurrentContextSlot), U8(4),
+  /*   93 S> */ B(LdaCurrentContextSlot), U8(4),
                 B(Star), R(1),
                 B(LdaSmi), I8(1),
                 B(DeletePropertyStrict), R(1),
   /*  113 S> */ B(Return),
 ]
 constant pool: [
   FIXED_ARRAY_TYPE,
   SHARED_FUNCTION_INFO_TYPE,
 ]
 handlers: [
 ]
 
 ---
 snippet: "
   return delete 'test';
 "
 frame size: 0
 parameter count: 1
 bytecode array length: 3
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   34 S> */ B(LdaTrue),
   /*   56 S> */ B(Return),
 ]
 constant pool: [
 ]
 handlers: [
 ]