Fix scopehositing with nested dynamic imports

packages/core/integration-tests/test/integration/scope-hoisting/es6/dynamic-import-dynamic/a.js

@@ -0,0 +1 @@
+export default import("./b.js").then(b => b.default);

packages/core/integration-tests/test/integration/scope-hoisting/es6/dynamic-import-dynamic/b.js

@@ -0,0 +1 @@
+export default import('./c.js').then(b => b.default + 1);

packages/core/integration-tests/test/integration/scope-hoisting/es6/dynamic-import-dynamic/c.js

@@ -0,0 +1 @@
+export default 122;

packages/core/integration-tests/test/scope-hoisting.js

@@ -264,6 +264,18 @@ describe('scope hoisting', function() {
       assert.equal(await output.default, 5);
     });
 
+    it('supports nested dynamic imports', async function() {
+      let b = await bundle(
+        path.join(
+          __dirname,
+          '/integration/scope-hoisting/es6/dynamic-import-dynamic/a.js'
+        )
+      );
+
+      let output = await run(b);
+      assert.equal(await output.default, 123);
+    });
+
     it('should not export function arguments', async function() {
       let b = await bundle(
         path.join(

packages/core/parcel-bundler/src/packagers/JSConcatPackager.js

@@ -384,6 +384,7 @@ class JSConcatPackager extends Packager {
     if (this.bundle.assets.has(asset)) {
       return;
     }
+    this.assets.set(asset.id, asset);
     this.bundle.addAsset(asset);
     if (!asset.parentBundle) {
       asset.parentBundle = this.bundle;