Reland "webrtc: update addIceCandidate() call to match spec"

This is a reland of ffc43d7a95f6b7843b3e476ab92bad05c8da669a
that also removes the (RTCIceCandidateInit or RTCIceCandidate) union
and the generated files from the build.

Original change's description:
> webrtc: update addIceCandidate() call to match spec
>
> see https://w3c.github.io/webrtc-pc/#interface-definition
> This allows addIceCandidate() as end-of-candidates indication. This is
> not yet implemented at the native layer.
>
> BUG=chromium:978582
>
> Change-Id: Id0f2acd2dcfdf4f5d311437df22c178c9d69630d
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2680823
> Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
> Reviewed-by: Guido Urdaneta <guidou@chromium.org>
> Reviewed-by: Harald Alvestrand <hta@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#852128}

Bug: chromium:978582
Change-Id: I889523b80b5a945efddf012d53c3a75d62b98f62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2684254
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Harald Alvestrand <hta@chromium.org>
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Cr-Commit-Position: refs/heads/master@{#853142}

webrtc/RTCPeerConnection-addIceCandidate.html

@@ -158,18 +158,28 @@
     null,
     // Members in the dictionary take their default values
     {}
-  ].forEach(init => promise_test(async t => {
-    const pc = new RTCPeerConnection();
+  ].forEach(init => {
+    promise_test(async t => {
+      const pc = new RTCPeerConnection();
 
-    t.add_cleanup(() => pc.close());
+      t.add_cleanup(() => pc.close());
 
-    await pc.setRemoteDescription(sessionDesc);
-    await pc.addIceCandidate(init);
-    assert_candidate_line_between(pc.remoteDescription.sdp,
-      mediaLine1, endOfCandidateLine, mediaLine2);
-    assert_candidate_line_after(pc.remoteDescription.sdp,
-      mediaLine2, endOfCandidateLine);
-  }, `addIceCandidate(${JSON.stringify(init)}) should work, and add a=end-of-candidates to both m-sections`));
+      await pc.setRemoteDescription(sessionDesc);
+      await pc.addIceCandidate(init);
+    }, `addIceCandidate(${JSON.stringify(init)}) works`);
+    promise_test(async t => {
+      const pc = new RTCPeerConnection();
+
+      t.add_cleanup(() => pc.close());
+
+      await pc.setRemoteDescription(sessionDesc);
+      await pc.addIceCandidate(init);
+      assert_candidate_line_between(pc.remoteDescription.sdp,
+        mediaLine1, endOfCandidateLine, mediaLine2);
+      assert_candidate_line_after(pc.remoteDescription.sdp,
+        mediaLine2, endOfCandidateLine);
+    }, `addIceCandidate(${JSON.stringify(init)}) adds a=end-of-candidates to both m-sections`);
+  });
 
   promise_test(async t => {
     const pc = new RTCPeerConnection();
@@ -418,7 +428,7 @@
       assert_candidate_line_between(pc.remoteDescription.sdp,
         mediaLine1, endOfCandidateLine, mediaLine2);
     });
-  }, 'Add with empty candidate string (end of candidate) should succeed');
+  }, 'Add with empty candidate string (end of candidates) should succeed');
 
   /*
     4.4.2.  addIceCandidate
@@ -440,6 +450,15 @@
         })));
   }, 'Add candidate with both sdpMid and sdpMLineIndex manually set to null should reject with TypeError');
 
+  promise_test(async t => {
+    const pc = new RTCPeerConnection();
+    t.add_cleanup(() => pc.close());
+
+    await pc.setRemoteDescription(sessionDesc);
+    promise_rejects_js(t, TypeError,
+      pc.addIceCandidate({candidate: candidateStr1}));
+  }, 'addIceCandidate with a candidate and neither sdpMid nor sdpMLineIndex should reject with TypeError');
+
   promise_test(t => {
     const pc = new RTCPeerConnection();
 
@@ -609,5 +628,4 @@
           usernameFragment: usernameFragment1
         })));
   }, 'Add candidate with sdpMid belonging to different usernameFragment should reject with OperationError');
-
 </script>