Create Web IDL watchlist and add myself to it

WATCHLISTS

Index: WATCHLISTS
diff --git a/WATCHLISTS b/WATCHLISTS
index 5c7414a61483b7808923ff41a46913f9e14a0000..6c8a6b0206d0515f8bf0ee92357933f40bcd0fb9 100644
--- a/WATCHLISTS
+++ b/WATCHLISTS
@@ -146,6 +146,9 @@
                   '|LayoutTests/fast/regions/' \
                   '|LayoutTests/platform/chromium.*/fast/regions/'
     },
+    'web_idl': {
+      'filepath': 'Source/core/.*\.idl'
+    },
     'webcomponents': {
       'filepath': 'Source/core/dom/shadow/.*' \
                   '|Source/core/dom/CustomElement.*' \
@@ -221,6 +224,7 @@
     'quota': [ 'kinuko@chromium.org' ],
     'viewport_interaction': [ 'kenneth.christiansen@gmail.com' ],
     'css_regions': [ 'ChromiumBugTracker@adobe.com' ],
+    'web_idl': [ 'ch.dumez@sisa.samsung.com' ],
     'webcomponents': [ 'webcomponents-bugzilla@chromium.org', 'dglazkov+blink@chromium.org' ],
     'mediastream': [ 'tommyw+watchlist@chromium.org' ],
   },