Add explicit [Exposed] to ReadableStreamDefaultController WebIDL

This CL adds an explicit [Exposed=(Window,Worker,Worklet)] declaration
to the ReadableStreamDefaultController WebIDL file as it was added
in a new version of the Streams spec, based on whatwg/streams#963.

Intent To Ship: https://groups.google.com/a/chromium.org/g/blink-dev/c/yZuxrW9zhAs/m/6bXDaW2mAwAJ

Bug: 1093862
Change-Id: I2bd0c759d856c176037231adbe7e679ccea945c8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570755
Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Nidhi Jaju <nidhijaju@google.com>
Cr-Commit-Position: refs/heads/master@{#837841}

workers/semantics/interface-objects/002.worker.js

@@ -22,7 +22,6 @@ var unexpected = [
   // https://streams.spec.whatwg.org/
   "ReadableStreamDefaultReader",
   "ReadableStreamBYOBReader",
-  "ReadableStreamDefaultController",
   "ReadableByteStreamController",
   "WritableStreamDefaultWriter",
   "WritableStreamDefaultController",

workers/semantics/interface-objects/004.any.js

@@ -20,7 +20,6 @@ var unexpected = [
   // https://streams.spec.whatwg.org/
   "ReadableStreamDefaultReader",
   "ReadableStreamBYOBReader",
-  "ReadableStreamDefaultController",
   "ReadableByteStreamController",
   "WritableStreamDefaultWriter",
   "WritableStreamDefaultController",