Notable Changes in Angular 9

1) Ivy applications: Previously, in applications, Hammer providers were included by default. With this commit, apps that want Hammer support must import HammerModule in their root module i.e.

 import {HAMMER_PROVIDERS} from './dom/events/hammer_gestures' 

2) ServiceWorker: Remove deprecated option versionedFiles from service worker asset group configuration in ngsw-config.json. 

3) Performance Improvements:

• Ivy: don’t store public input names in two places.
• Ivy: fix creation time micro-benchmarks.
• Ivy: Improve performance of transplanted views.
• Ivy: avoid native node retrieval from LView.
• Ivy: avoid repeated native node retrieval and patching.
• Ivy:avoid repeated tNode.initialInputs reads.
• Ivy:move local references into consts array.
• Ivy: R3TestBed – Do not process NgModuleDefs that have already been processed.

Bug Fixes

1) Common: update $locationShim to notify onChange listeners before emitting AngularJS events.

2) Compiler: return enableIvy true when using readConfiguration.

3) Ivy:

• Get name directly from nativeNode.
• Handle empty bindings in template type checker.
• In ngcc, handle inline exports in commonjs code.
• The ngcc should only index .d.ts exports within the package.
• The ngTemplateOutlet error when switching between null and template value.

4) language-service:

• Instantiate MetadataResolver once.
• Remove "context" used for module resolution. 

5) Ngcc:

• Handle deep imports that already have an extension.
• Ignore format properties that exit but are undefined.