Reland: [modules] Properly initialize declared variables.

src/parsing/parser.h

Index: src/parsing/parser.h
diff --git a/src/parsing/parser.h b/src/parsing/parser.h
index 86680e1683d713dcb112b0cafe99cdc7cd1723f6..fceaa2ff3579b72233d966ba76f33d03b7725787 100644
--- a/src/parsing/parser.h
+++ b/src/parsing/parser.h
@@ -216,6 +216,8 @@ class Parser : public ParserBase<Parser> {
     return scope()->NewTemporary(name);
   }
 
+  void PrepareGeneratorVariables(FunctionState* function_state);
+
   // Limit the allowed number of local variables in a function. The hard limit
   // is that offsets computed by FullCodeGenerator::StackOperand and similar
   // functions are ints, and they should not overflow. In addition, accessing
@@ -575,6 +577,7 @@ class Parser : public ParserBase<Parser> {
   friend class InitializerRewriter;
   void RewriteParameterInitializer(Expression* expr, Scope* scope);
 
+  Expression* BuildInitialYield(int pos, FunctionKind kind);
   Expression* BuildCreateJSGeneratorObject(int pos, FunctionKind kind);
   Expression* BuildResolvePromise(Expression* value, int pos);
   Expression* BuildRejectPromise(Expression* value, int pos);