cmd/heapview: add karma+jasmine TS unit testing config

Add a configuration that allows unit testing of client Typescript
code using Karma and Jasmine. Add a basic test to exercise this.

Change-Id: I88af82b68547423efeaafb0fab8214ed39573ee9
Reviewed-on: https://go-review.googlesource.com/25411
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Evan Martin <evanm@google.com>
7 files changed