[turbofan] Mark loads of a module (from a module context) immutable.

src/compiler/bytecode-graph-builder.cc

Index: src/compiler/bytecode-graph-builder.cc
diff --git a/src/compiler/bytecode-graph-builder.cc b/src/compiler/bytecode-graph-builder.cc
index bafc0e7a9da446f4b42575a5e068cdc6dd1d92f4..c24494d7afa0595760ddec79a7b24133316768c6 100644
--- a/src/compiler/bytecode-graph-builder.cc
+++ b/src/compiler/bytecode-graph-builder.cc
@@ -1068,8 +1068,8 @@ void BytecodeGraphBuilder::VisitStaKeyedPropertyStrict() {
 void BytecodeGraphBuilder::VisitLdaModuleVariable() {
   int32_t cell_index = bytecode_iterator().GetImmediateOperand(0);
   uint32_t depth = bytecode_iterator().GetUnsignedImmediateOperand(1);
-  Node* module = NewNode(
-      javascript()->LoadContext(depth, Context::EXTENSION_INDEX, false));
+  Node* module =
+      NewNode(javascript()->LoadContext(depth, Context::EXTENSION_INDEX, true));
   Node* value = NewNode(javascript()->LoadModule(cell_index), module);
   environment()->BindAccumulator(value);
 }
@@ -1077,8 +1077,8 @@ void BytecodeGraphBuilder::VisitLdaModuleVariable() {
 void BytecodeGraphBuilder::VisitStaModuleVariable() {
   int32_t cell_index = bytecode_iterator().GetImmediateOperand(0);
   uint32_t depth = bytecode_iterator().GetUnsignedImmediateOperand(1);
-  Node* module = NewNode(
-      javascript()->LoadContext(depth, Context::EXTENSION_INDEX, false));
+  Node* module =
+      NewNode(javascript()->LoadContext(depth, Context::EXTENSION_INDEX, true));
   Node* value = environment()->LookupAccumulator();
   NewNode(javascript()->StoreModule(cell_index), module, value);
 }