Remove Demitasse test resolver

This is not needed at all. We can just import temporal.mjs in the one
place in the Demitasse tests where we need a Temporal object. (One other
place, it was imported unnecessarily; remove that.)

Author: ptomato

polyfill/package.json

@@ -7,7 +7,7 @@
   "browser": "dist/index.umd.js",
   "types": "index.d.ts",
   "scripts": {
-    "test": "node --loader ./test/resolve.source.mjs ./test/all.mjs",
+    "test": "node ./test/all.mjs",
     "test-cookbook": "npm run build && TEST=all npm run test-cookbook-one",
     "test-cookbook-one": "node --loader ./test/resolve.cookbook.mjs ../docs/cookbook/$TEST.mjs",
     "test262": "npm run build262 && node runtest262.mjs",

polyfill/test/datemath.mjs

@@ -14,7 +14,7 @@ const { reporter } = Pretty;
 import { strict as assert } from 'assert';
 const { equal } = assert;
 
-import * as Temporal from 'proposal-temporal';
+import * as Temporal from '../lib/temporal.mjs';
 
 describe('Date.since(simple, simple)', () => {
   build('Before Leap Day', '2020-01-03', '2020-02-15');

polyfill/test/ecmascript.mjs

@@ -10,7 +10,6 @@ const { deepEqual, equal, throws } = assert;
 import bigInt from 'big-integer';
 import { readFileSync } from 'fs';
 
-import 'proposal-temporal';
 import * as ES from '../lib/ecmascript.mjs';
 
 describe('ECMAScript', () => {