Typescript doesn't add .js extension to the imported file name. As a
result, the browser imports the same file twice with different names:
for example app-context and app-context.js. After the fix, server.go
patches the typescript output and adds .js extension. Rollup handles
such cases correctly.
Change-Id: I3290f9244bb6d6dd8547fbceed8ed57186c6f638