🐛 Resolves the referenced element before parsing colors

[AlexV525]

Fixes #5436.

Before	After

Implementation details

• Colors and CupertinoColors are hard-coded to determine colored element. The condition has been removed, which means all elements will be predicated.
• Referenced will be resolved before the element gets parsed by text directly.
• All the additional checks will be called only if the element type is VAR_INIT (for declarations) or FUNCTION_BODY (for getters) to avoid too much performance regression.

Test case:

import 'package:flutter/material.dart' hide Colors;

const Color _c1 = Color(0xff000000);
final _c2 = _c1;
Color get _c3 => _c2;

void test() {
  const Color c1 = _c1;
  const Color c2 = Color(0xffffffff);
  const Color c3 = Color.fromARGB(255, 123, 231, 31);
  const Color c4 = Color(0xff923998);
  const Color c5 = c2;
  const Color c6 = TC.c1;
  const Color c7 = TC.c2;
  const Color c8 = TC.c3;
  const Color c9 = Colors.black;
}

class TC {
  static const Color c1 = Color(0xff449978);
  static const Color c2 = Color(0xffdb2f7f);
  static const Color c3 = Color.fromARGB(150, 66, 231, 31);
}

class Colors {
  static const Color white = Color(0xffaa9933);
  static const Color tests = Colors.white;
  static const Color black = Colors.tests;
  static const Color tcC1 = TC.c1;
  final Color tcC2 = TC.c2;
  Color get tcC3 => TC.c3;
}

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read the Flutter Style Guide recently, and have followed its advice.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

[stevemessick]

Nice!

[stevemessick]

I'm going to include this in the next release.