grpc-js-core: ignore reserved headers in fromHttp2Headers()

Metadata.fromHttp2Headers() throws if any reserved headers
are passed. Instead of deleting headers before calling the
function, this commit causes the function to ignore reserved
headers.

packages/grpc-js-core/src/call-stream.ts

@@ -233,8 +233,7 @@ export class Http2CallStream extends Duplex implements Call {
           default:
             this.mappedStatusCode = Status.UNKNOWN;
         }
-        delete headers[HTTP2_HEADER_STATUS];
-        delete headers[HTTP2_HEADER_CONTENT_TYPE];
+
         if (flags & http2.constants.NGHTTP2_FLAG_END_STREAM) {
           this.handleTrailers(headers);
         } else {

packages/grpc-js-core/src/metadata.ts

@@ -197,6 +197,11 @@ export class Metadata {
   static fromHttp2Headers(headers: http2.IncomingHttpHeaders): Metadata {
     const result = new Metadata();
     forOwn(headers, (values, key) => {
+      // Reserved headers (beginning with `:`) are not valid keys.
+      if (key.charAt(0) === ':') {
+        return;
+      }
+
       if (isBinaryKey(key)) {
         if (Array.isArray(values)) {
           values.forEach((value) => {