add getbase gtype method

this method gets the closest parent gtype that is registered in gobject-introspection. this is because classes registed manually (in deno_gi) can't be constructed from their GBaseInfo. In the future, we will probably need to maintain a reference to the manually registed classes so they can be constructed from reference.

src/utils/gobject.js

@@ -1,4 +1,4 @@
-import { GIInfoType } from "../bindings/enums.js";
+import { GIInfoType, GType } from "../bindings/enums.js";
 import g from "../bindings/mod.js";
 import { createEnum } from "../types/enum.js";
 import { createInterface } from "../types/interface.js";
@@ -7,7 +7,24 @@ import { createStruct } from "../types/struct.js";
 
 export const cache = new Map();
 
-export function objectByGType(gType) {
+// find a registered gType. Sometimes, gTypes may not be available as GObjectInfo
+// because they were registered as a static type. now what is done is that
+// we get the closest gType that is available in gobject-introspection
+// TODO: handle these nicely
+function getBaseGType(gType) {
+  if (!g.type.is_a(gType, GType.OBJECT)) return null;
+
+  let baseGType = gType;
+  while (!g.irepository.find_by_gtype(null, baseGType)) {
+    baseGType = g.type.parent(baseGType);
+  }
+
+  return baseGType;
+}
+
+export function objectByGType(_gType) {
+  const gType = getBaseGType(_gType);
+
   if (cache.has(gType)) {
     return cache.get(gType);
   }