[dart2wasm] Implement function tear-offs
[dart2wasm] Implement function tear-offs

New passing tests:

- co19/LanguageFeatures/Constructor-tear-offs/call_method_A01_t01
- co19/LanguageFeatures/Constructor-tear-offs/call_method_A01_t02
- co19/LanguageFeatures/Constructor-tear-offs/call_method_A02_t01
- co19/LanguageFeatures/Constructor-tear-offs/call_method_A02_t02
- co19/LanguageFeatures/Constructor-tear-offs/call_method_A02_t03
- co19/LanguageFeatures/Constructor-tear-offs/call_method_A02_t07
- co19/LanguageFeatures/Constructor-tear-offs/call_method_A03_t01
- co19/LanguageFeatures/Constructor-tear-offs/call_method_A04_t02
- co19/LanguageFeatures/Constructor-tear-offs/syntax_A03_t01
- language/call/method_function_typed_value_test/02
- language/call/method_function_typed_value_test/04
- language/call/method_function_typed_value_test/06
- language/generic/generic_function_type_argument_test

Change-Id: I247a6fc70e707339315a780040f344e89ac78005
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/267320
Commit-Queue: Ömer Ağacan <d15e39adaef0c3a64e4ea5d68f5c1b5be1f04e29@google.com>
Reviewed-by: Aske Simon Christensen <589eb3fd9a84f06d0ac46d3aa71dddcfb0814ccd@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk