Commented IDL implements statements should not generate code

Source/bindings/scripts/preprocess_idls.py

Index: Source/bindings/scripts/preprocess_idls.py
diff --git a/Source/bindings/scripts/preprocess_idls.py b/Source/bindings/scripts/preprocess_idls.py
index 4603df304141bfefa328e5ce83f7b8f053ff19ab..2e330445461f5595435419c2f1e616644eb3eb35 100644
--- a/Source/bindings/scripts/preprocess_idls.py
+++ b/Source/bindings/scripts/preprocess_idls.py
@@ -74,7 +74,7 @@ def get_partial_interface_name_from_idl(file_contents):
 # http://www.w3.org/TR/WebIDL/#idl-implements-statements
 def get_implemented_interfaces_from_idl(file_contents, interface_name):
     implemented_interfaces = []
-    for match in re.finditer(r'(\w+)\s+implements\s+(\w+)\s*;', file_contents):
+    for match in re.finditer(r'^\s*(\w+)\s+implements\s+(\w+)\s*;', file_contents, re.MULTILINE):
         # identifier-A must be the current interface
         assert match.group(1) == interface_name, \
 "Identifier on the left of the 'implements' statement should be %s in %s.idl, but found %s" % (interface_name, interface_name, match.group(1))