Revert of Thread maybe-assigned through the bytecodes.

src/interpreter/bytecode-generator.cc

Index: src/interpreter/bytecode-generator.cc
diff --git a/src/interpreter/bytecode-generator.cc b/src/interpreter/bytecode-generator.cc
index 75497cf2c16738f53ac9c24a8b01c94ea90ec75f..c28d4687d8a8cf5b742626739d8cbeb50ee9dc54 100644
--- a/src/interpreter/bytecode-generator.cc
+++ b/src/interpreter/bytecode-generator.cc
@@ -1942,13 +1942,7 @@
         context_reg = execution_context()->reg();
       }
 
-      BytecodeArrayBuilder::ContextSlotMutability immutable =
-          (variable->maybe_assigned() == kNotAssigned)
-              ? BytecodeArrayBuilder::kImmutableSlot
-              : BytecodeArrayBuilder::kMutableSlot;
-
-      builder()->LoadContextSlot(context_reg, variable->index(), depth,
-                                 immutable);
+      builder()->LoadContextSlot(context_reg, variable->index(), depth);
       if (hole_check_mode == HoleCheckMode::kRequired) {
         BuildThrowIfHole(variable->name());
       }
@@ -2112,8 +2106,7 @@
         Register value_temp = register_allocator()->NewRegister();
         builder()
             ->StoreAccumulatorInRegister(value_temp)
-            .LoadContextSlot(context_reg, variable->index(), depth,
-                             BytecodeArrayBuilder::kMutableSlot);
+            .LoadContextSlot(context_reg, variable->index(), depth);
 
         BuildHoleCheckForVariableAssignment(variable, op);
         builder()->LoadAccumulatorWithRegister(value_temp);
@@ -2744,11 +2737,9 @@
         Register global_object = register_allocator()->NewRegister();
         builder()
             ->LoadContextSlot(execution_context()->reg(),
-                              Context::NATIVE_CONTEXT_INDEX, 0,
-                              BytecodeArrayBuilder::kMutableSlot)
+                              Context::NATIVE_CONTEXT_INDEX, 0)
             .StoreAccumulatorInRegister(native_context)
-            .LoadContextSlot(native_context, Context::EXTENSION_INDEX, 0,
-                             BytecodeArrayBuilder::kMutableSlot)
+            .LoadContextSlot(native_context, Context::EXTENSION_INDEX, 0)
             .StoreAccumulatorInRegister(global_object)
             .LoadLiteral(variable->name())
             .Delete(global_object, language_mode());
@@ -3260,18 +3251,15 @@
     Register native_context = register_allocator()->NewRegister();
     builder()
         ->LoadContextSlot(execution_context()->reg(),
-                          Context::NATIVE_CONTEXT_INDEX, 0,
-                          BytecodeArrayBuilder::kMutableSlot)
+                          Context::NATIVE_CONTEXT_INDEX, 0)
         .StoreAccumulatorInRegister(native_context)
-        .LoadContextSlot(native_context, Context::CLOSURE_INDEX, 0,
-                         BytecodeArrayBuilder::kMutableSlot);
+        .LoadContextSlot(native_context, Context::CLOSURE_INDEX, 0);
   } else if (closure_scope->is_eval_scope()) {
     // Contexts created by a call to eval have the same closure as the
     // context calling eval, not the anonymous closure containing the eval
     // code. Fetch it from the context.
     builder()->LoadContextSlot(execution_context()->reg(),
-                               Context::CLOSURE_INDEX, 0,
-                               BytecodeArrayBuilder::kMutableSlot);
+                               Context::CLOSURE_INDEX, 0);
   } else {
     DCHECK(closure_scope->is_function_scope() ||
            closure_scope->is_module_scope());