Fix circular import

Author: StoneDot

packages/opencensus-instrumentation-http2/src/http2.ts

@@ -23,6 +23,7 @@ import {
   SpanKind,
   TraceOptions,
 } from '@opencensus/core';
+import 'http';
 import { HttpPlugin } from '@opencensus/instrumentation-http';
 import * as http2 from 'http2';
 import * as shimmer from 'shimmer';

packages/opencensus-instrumentation-https/src/https.ts

@@ -15,6 +15,7 @@
  */
 
 import { Func } from '@opencensus/core';
+import 'http';
 import { HttpPlugin } from '@opencensus/instrumentation-http';
 import * as http from 'http';
 import * as https from 'https';