[ignition,modules] Introduce bytecodes for loading/storing module variables.

src/code-stub-assembler.h

Index: src/code-stub-assembler.h
diff --git a/src/code-stub-assembler.h b/src/code-stub-assembler.h
index 869afe42ab4b068712f26435a0913063ee1c1fec..c6a76138d47301a41f7ce737881424ac4ffb35f4 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -334,6 +334,7 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   compiler::Node* StoreContextElement(compiler::Node* context, int slot_index,
                                       compiler::Node* value);
   compiler::Node* LoadNativeContext(compiler::Node* context);
+  compiler::Node* LoadModuleContext(compiler::Node* context);
 
   compiler::Node* LoadJSArrayElementsMap(ElementsKind kind,
                                          compiler::Node* native_context);