[dart:html] Update changes in idl_parser location

Simply adds the new location to the sys.path so it can be found
and filters idl files within idl_parser so it doesn't affect
codegen. Also removes a stale comment to finalize the python3
migration.

Change-Id: I31d93fd8de22e38a0e968587149546565f86e3ba
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/212630
Reviewed-by: Riley Porter <rileyporter@google.com>

tools/dom/scripts/dartdomgenerator.py

@@ -31,12 +31,11 @@ if not os.path.exists(ply_dir):
     third_party_dir = os.path.join(dart_dir, '..', 'third_party')
     assert (os.path.exists(third_party_dir))
 else:
-    # It's Dart we need to make sure that tools in injected in our search path
-    # because this is where idl_parser is located for a Dart enlistment.  Dartium
+    # It's Dart we need to make sure that WebCore is injected in our search path
+    # because this is where idl_parser is located for a Dart enlistment. Dartium
     # can figure out the tools directory because of the location of where the
     # scripts blink scripts are located.
-    tools_dir = os.path.join(dart_dir, 'tools')
-    sys.path.insert(1, tools_dir)
+    sys.path.insert(1, os.path.join(dart_dir, 'third_party/WebCore'))
 
 sys.path.insert(1, third_party_dir)
 

tools/dom/scripts/fremontcutbuilder.py

@@ -183,6 +183,7 @@ def main(parallel=False, logging_level=logging.WARNING, examine_idls=False):
         'networkinfo',  # Not yet used in Blink yet
         'vibration',  # Not yet used in Blink yet
         'inspector',
+        'idl_parser',  # idl_parser has test IDL files.
     ]
 
     # TODO(terry): Integrate this into the htmlrenamer's _removed_html_interfaces

tools/dom/scripts/go.sh

@@ -35,7 +35,5 @@ if [[ "$1" != "" ]] ; then
   fi
 fi
 
-# third_party IDL scripts are not compatible with python3, so use python2.7.
-
 reset && \
 python3 ./dartdomgenerator.py --systems="$SYSTEMS" --logging=40 --update-dom-metadata --gen-interop "$ARG_OPTION"