[parsing] When failing due to variable redeclaration, point at the variable.

src/parsing/parser.h

Index: src/parsing/parser.h
diff --git a/src/parsing/parser.h b/src/parsing/parser.h
index 37dc0d8a6754ed2efa0eb386c7200ce8e6517421..3d81698de259b921ee26ec4d0ef3f1134c94e8fb 100644
--- a/src/parsing/parser.h
+++ b/src/parsing/parser.h
@@ -468,7 +468,8 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
   Variable* Declare(Declaration* declaration,
                     DeclarationDescriptor::Kind declaration_kind,
                     VariableMode mode, InitializationFlag init, bool* ok,
-                    Scope* declaration_scope = nullptr);
+                    Scope* declaration_scope = nullptr,
+                    int var_end_pos = kNoSourcePosition);
   Declaration* DeclareVariable(const AstRawString* name, VariableMode mode,
                                int pos, bool* ok);
   Declaration* DeclareVariable(const AstRawString* name, VariableMode mode,