util: move common proxyobserver attributes to the base class
Fixes the following pytype warnings:
line 791, in _writedata: No attribute 'logdata' on baseproxyobserver [attribute-error]
line 792, in _writedata: No attribute 'logdataapis' on baseproxyobserver [attribute-error]
line 793, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
line 794, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
line 799, in _writedata: No attribute 'logdataapis' on baseproxyobserver [attribute-error]
line 800, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
line 802, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
line 803, in _writedata: No attribute 'name' on baseproxyobserver [attribute-error]
line 805, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
line 809, in _writedata: No attribute 'logdataapis' on baseproxyobserver [attribute-error]
line 810, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
line 814, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
line 815, in _writedata: No attribute 'name' on baseproxyobserver [attribute-error]
line 817, in _writedata: No attribute 'fh' on baseproxyobserver [attribute-error]
Differential Revision: https://phab.mercurial-scm.org/D7675
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}