This issue was originally filed by smok@google.com

Quick summary of various ideas to improve dart2dart minifier efficiency.

1. Remove import prefixes where possible and/or optimize import prefixes. Now we always import platform libraries with prefix, and that's at least +2 chars on each usage. Often imports are 2-3 char strings. However the size impact of that is small.
2. Combine several declarations into one:
   "final a = 5; final b = 6;" => "final a=5,b=6";
3. Inline methods that are used only once.
4. Create short aliases for methods from platform libs that are often used, create short getters for fields. Example: "putIfAbsent", "containsKey". But this may affect performance.
5. Reuse static fields and methods names. We can also try to reuse non-static member names, but that should be done carefully, we need to infer types for dynamic calls.

Smaller ideas:

1. Stripped types still leave unnecessary whitespaces:
   "void foo(var a) {}" => "foo( a){}"
2. Make 1-char constants for "null", "true", "false". (~3%)
3. Strip type arguments, this is minor: "new A<B,C>();" => "new A();" (would save <1% of output)
4. Change "final" to "var" where possible (<1%)
5. Strip types in for expressions: "for(int a in list)" => "for(a in list)"