Update json_schema_compiler to handle the Automation extension API

tools/json_schema_compiler/js_util.py

Index: tools/json_schema_compiler/js_util.py
diff --git a/tools/json_schema_compiler/js_util.py b/tools/json_schema_compiler/js_util.py
index 2549aefa2fae4966eee2c0f1fe4fef67667b82a7..60c52626c316bc3410b17b6818b48c377c35f052 100644
--- a/tools/json_schema_compiler/js_util.py
+++ b/tools/json_schema_compiler/js_util.py
@@ -101,6 +101,18 @@ class JsUtil(object):
 
     c.Eblock(' */')
 
+  def AppendTypeJsDoc(self, c, namespace_name, js_type, nullable):
+    """Appends the documentation for a type as a Code.
+    """
+    c.Append('@type {')
+    js_type_str = self._TypeToJsType(namespace_name, js_type).Render()
+    if nullable:
+      if js_type_str[0] == '!':
+        js_type_str = js_type_str[1:]
+      js_type_str = '?' + js_type_str

[Devlin, 2017/01/12 17:28:48]

Note: This means the possible values for the type are existent or null, but
*not* undefined.  Since undefined is the default value in js for nonexistent
properties on an object, it seems like maybe this should be either:
?foo|undefined   -> null, undefined, or existent
or
!foo|undefined   -> undefined or existent, not null

In my experience, usually the latter is sufficient, but I'm not sure how all of
automation uses it.

[dmazzoni, 2017/01/13 21:22:54]

You're totally right.

Pretty much everything returned from our native bindings
should either be existent or undefined, with a couple of
things that we can guarantee are existent.

In IDL the only thing we can express is "optional", but
that should translate into !foo|undefined, not ?foo.

That's also consistent with how js_externs_generator
is handling optional fields in record types, too.

Fixed.

I also renamed "nullable" back to "optional" in the
json_schema_compiler code.

+    c.Append(js_type_str, new_line=False)
+    c.Append('}', new_line=False)
+
   def _FunctionToJsFunction(self, namespace_name, function):
     """Converts a model.Function to a JS type (i.e., function([params])...)"""
     c = Code()