fix(@ngtools/webpack): add parent nodes and keep program

Technically that program should always be the valid one, and is needed in some cases (e.g. diagnostics).
Adding parent nodes get rid of the getChildAt error that happens, because the prop.parent is not
set.

The issue happened because people are using "files": ["main.ts"] or something similar, and when we load
another file than main we dont set the parent nodes.

Fixes #5143
Fixes #4817

Author: hansl

packages/@ngtools/webpack/src/loader.spec.ts

@@ -34,6 +34,27 @@ describe('@ngtools/webpack', () => {
         expect(refactor2.sourceText).toMatch(/\(\{\s*otherValue2: 2\s*,\s*otherValue3: 3\s*}\)/);
         expect(refactor2.sourceText).toMatch(/\(\{\s*otherValue4: 4\s*}\)/);
       });
+
+      it('should work without a root name', () => {
+        const host = new WebpackCompilerHost({}, '');
+        host.writeFile('/file.ts', `
+          import './file2.ts';
+        `, false);
+        host.writeFile('/file2.ts', `
+          @SomeDecorator({ moduleId: 123 }) class CLS {}
+          @SomeDecorator({ moduleId: 123, otherValue1: 1 }) class CLS2 {}
+          @SomeDecorator({ otherValue2: 2, moduleId: 123, otherValue3: 3 }) class CLS3 {}
+          @SomeDecorator({ otherValue4: 4, moduleId: 123 }) class CLS4 {}
+        `, false);
+
+        const program = ts.createProgram(['/file.ts'], {}, host);
+        const refactor = new TypeScriptFileRefactor('/file2.ts', host, program);
+        removeModuleIdOnlyForTesting(refactor);
+        expect(refactor.sourceText).toMatch(/\(\{\s+}\)/);
+        expect(refactor.sourceText).toMatch(/\(\{\s*otherValue1: 1\s*}\)/);
+        expect(refactor.sourceText).toMatch(/\(\{\s*otherValue2: 2\s*,\s*otherValue3: 3\s*}\)/);
+        expect(refactor.sourceText).toMatch(/\(\{\s*otherValue4: 4\s*}\)/);
+      });
     });
   });
 });

packages/@ngtools/webpack/src/refactor.ts

@@ -45,9 +45,8 @@ export class TypeScriptFileRefactor {
       this._sourceFile = _program.getSourceFile(fileName);
     }
     if (!this._sourceFile) {
-      this._program = null;
       this._sourceFile = ts.createSourceFile(fileName, _host.readFile(fileName),
-        ts.ScriptTarget.Latest);
+        ts.ScriptTarget.Latest, true);
     }
     this._sourceText = this._sourceFile.getFullText(this._sourceFile);
     this._sourceString = new MagicString(this._sourceText);