fix(@ngtools/webpack): fix elide removing whole imports on single match

If an import imports multiple symbols, the previous condition meant that the whole
import statement was removed, instead of only the symbol.

Fixes #8518.

Author: hansl

packages/@ngtools/webpack/src/transformers/elide_imports.ts

@@ -113,7 +113,7 @@ export function elideImports(
     })
     .forEach((symbol) => {
       // Remove the whole declaration if it's a single import.
-      const nodeToRemove = symbol.singleImport ? symbol.importSpec : symbol.importDecl;
+      const nodeToRemove = symbol.singleImport ? symbol.importDecl : symbol.importSpec;
       ops.push(new RemoveNodeOperation(sourceFile, nodeToRemove));
     });
 

packages/@ngtools/webpack/src/transformers/remove_decorators.spec.ts

@@ -108,5 +108,41 @@ describe('@ngtools/webpack transformers', () => {
 
       expect(oneLine`${result}`).toEqual(oneLine`${output}`);
     });
+
+    it('should not remove imports from types that are still used', () => {
+      const input = stripIndent`
+        import { Component, EventEmitter } from '@angular/core';
+
+        @Component({
+          selector: 'app-root',
+          changeDetection: ChangeDetectionStrategy.OnPush,
+          templateUrl: './app.component.html',
+          styleUrls: ['./app.component.css']
+        })
+        export class AppComponent {
+          notify: EventEmitter<string> = new EventEmitter<string>();
+          title = 'app';
+        }
+      `;
+      const output = stripIndent`
+        import { EventEmitter } from '@angular/core';
+
+        export class AppComponent {
+          constructor() {
+            this.notify = new EventEmitter();
+            this.title = 'app';
+          }
+        }
+      `;
+
+      const { program, compilerHost } = createTypescriptContext(input);
+      const transformer = removeDecorators(
+        () => true,
+        () => program.getTypeChecker(),
+      );
+      const result = transformTypescript(undefined, [transformer], program, compilerHost);
+
+      expect(oneLine`${result}`).toEqual(oneLine`${output}`);
+    });
   });
 });