Revert "mojo-js: Use bound generic type for PendingReceiver"

This reverts commit 216a16f9.

Reason for revert: See https://bugs.chromium.org/p/chromium/issues/detail?id=1044378#c5

Original change's description:
> mojo-js: Use bound generic type for PendingReceiver
>
> The Closure version used in Chromium now supports bounded generic types.
>
> Bug: 1015726
> Change-Id: I14c080b6e3cd67cbdf564312fc1c1686f3adb1e6
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1906691
> Commit-Queue: Giovanni Ortuño Urquidi <ortuno@chromium.org>
> Reviewed-by: Ken Rockot <rockot@google.com>
> Cr-Commit-Position: refs/heads/master@{#714744}

TBR=rockot@google.com,ortuno@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1015726,1044378
Change-Id: Ic08c9baa69db14d9abf7a6f0ca64e4f9720b7cd4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2017902
Auto-Submit: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#735161}

mojo/public/js/interface_support.js

@@ -166,12 +166,13 @@ mojo.internal.interfaceSupport.PendingReceiver = class {
  * serialize requests and deserialize their replies, both according to
  * declarative message structure specs.
  *
- * @template {!mojo.internal.interfaceSupport.PendingReceiver} T
+ * TODO(crbug.com/1012109): Use a bounded generic type instead of
+ * mojo.internal.interfaceSupport.PendingReceiver.
  * @export
  */
 mojo.internal.interfaceSupport.InterfaceRemoteBase = class {
   /**
-   * @param {!function(new:T, !MojoHandle)} requestType
+   * @param {!function(new:mojo.internal.interfaceSupport.PendingReceiver, !MojoHandle)} requestType
    * @param {MojoHandle=} opt_handle The message pipe handle to use as a remote
    *     endpoint. If null, this object must be bound with bindHandle before
    *     it can be used to send any messages.
@@ -181,7 +182,7 @@ mojo.internal.interfaceSupport.InterfaceRemoteBase = class {
     /** @public {?MojoHandle} */
     this.handle = null;
 
-    /** @private {!function(new:T, !MojoHandle)} */
+    /** @private {!function(new:mojo.internal.interfaceSupport.PendingReceiver, !MojoHandle)} */
     this.requestType_ = requestType;
 
     /** @private {?mojo.internal.interfaceSupport.HandleReader} */
@@ -207,7 +208,7 @@ mojo.internal.interfaceSupport.InterfaceRemoteBase = class {
   }
 
   /**
-   * @return {!T}
+   * @return {!mojo.internal.interfaceSupport.PendingReceiver}
    */
   bindNewPipeAndPassReceiver() {
     let {handle0, handle1} = Mojo.createMessagePipe();