IDL: Put [Exposed=Window] where it's not in Blink's renderer/modules/plugins

Though Web IDL spec removed [PrimaryGlobal] and made [Exposed] required [1],
many blink's IDL files have not followed it yet. So, this CL adds the keyword
to the IDL files which don't have the keyword yet in the renderer/module/payments
directory. Additionally, this CL updates the URLs of the specificiations.

[1] https://github.com/heycam/webidl/issues/365

Bug: 963267
Change-Id: I6fdaba4bac93e7538756ccb8b931261035c2ad1d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1670667Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#671502}

third_party/blink/renderer/modules/plugins/mime_type.idl

@@ -18,7 +18,10 @@
     Boston, MA 02110-1301, USA.
 */
 
+// https://html.spec.whatwg.org/multipage/system-state.html#mimetype
+
 [
+    Exposed=Window,
     ImplementedAs=DOMMimeType
 ] interface MimeType {
     readonly attribute DOMString type;

third_party/blink/renderer/modules/plugins/mime_type_array.idl

@@ -18,7 +18,10 @@
     Boston, MA 02110-1301, USA.
 */
 
+// https://html.spec.whatwg.org/multipage/system-state.html#mimetypearray
+
 [
+    Exposed=Window,
     ImplementedAs=DOMMimeTypeArray,
     LegacyUnenumerableNamedProperties
 ] interface MimeTypeArray {

third_party/blink/renderer/modules/plugins/plugin.idl

@@ -18,9 +18,10 @@
     Boston, MA 02110-1301, USA.
 */
 
-// https://html.spec.whatwg.org/C/#plugins-2
+// https://html.spec.whatwg.org/multipage/system-state.html#dom-plugin
 
 [
+    Exposed=Window,
     ImplementedAs=DOMPlugin,
     LegacyUnenumerableNamedProperties
 ] interface Plugin {

third_party/blink/renderer/modules/plugins/plugin_array.idl

@@ -18,9 +18,10 @@
     Boston, MA 02110-1301, USA.
 */
 
-// https://html.spec.whatwg.org/C/#plugins-2
+// https://html.spec.whatwg.org/multipage/system-state.html#pluginarray
 
 [
+    Exposed=Window,
     ImplementedAs=DOMPluginArray,
     LegacyUnenumerableNamedProperties
 ] interface PluginArray {