bind-gen: Implement IDL constants

Bug: 839389
Change-Id: Ibb8351683cb95481e5e4d293dca499479f7beaaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1980656
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727150}

third_party/blink/renderer/bindings/scripts/bind_gen/name_style.py

@@ -132,19 +132,29 @@ def namespace_f(format_string, *args, **kwargs):
 def _concat(style_func, args):
     assert callable(style_func)
 
-    return style_func(" ".join(map(str, args)))
+    return style_func(" ".join(map(_tokenize, args)))
 
 
 def _format(style_func, format_string, *args, **kwargs):
     assert callable(style_func)
     assert isinstance(format_string, str)
 
-    args = map(style_func, map(str, args))
+    args = map(style_func, map(_tokenize, args))
     for key, value in kwargs.iteritems():
-        kwargs[key] = style_func(str(value))
+        kwargs[key] = style_func(_tokenize(value))
     return format_string.format(*args, **kwargs)
 
 
+def _tokenize(s):
+    s = str(s)
+    if "_" in s and s.isupper():
+        # NameStyleConverter doesn't treat "ABC_DEF" as two tokens of "abc" and
+        # "def" while treating "abc_def" as "abc" and "def".  Help
+        # NameStyleConverter by lowering the string.
+        return s.lower()
+    return s
+
+
 class raw(object):
     """
     Namespace to provide (unrecommended) raw controls on case conversions.

third_party/blink/renderer/bindings/scripts/web_idl/constant.py

@@ -66,6 +66,14 @@ class Constant(WithIdentifier, WithExtendedAttributes, WithCodeGeneratorInfo,
         """Returns the type"""
         return self._idl_type
 
+    @property
+    def is_static(self):
+        return True
+
+    @property
+    def is_readonly(self):
+        return True
+
     @property
     def value(self):
         """Returns the value."""