dict.update should return None, not self #18
Description
In .bzl files, the expression dict(a=1).update(b=2) evaluates to {a: 1, b: 2} but according to
https://github.com/bazelbuild/starlark/blob/master/spec.md#dictupdate
it should return None.
Both Pythons and Starlark-in-Go return None:
$ python # 2 or 3
x = {}
x.update(k=1)
x
{'k': 1}
$ starlark # in Go
x = {}
x.update(k=1)
x
{"k": 1}
The Java standalone interpreter gives a strange error --- I have no idea what it means:
% blaze-bin/third_party/bazel/src/main/java/com/google/devtools/skylark/Skylark
x = {}
x.update(k=1)
parameter 'other' has no default value, in method call update(int k) of 'dict'
Googlers: see L23 of dart_dev_ctx.bzl in cr/223363742 for a real-world example.