Currently every FlowModel creates a new empty map that's just supposed
to be empty. When compiling `compile.dart` (from the CFE) this creates
more than 200,000 maps for seemingly no reason.
This CL removes it, thus saving the creation of (...instrumenting the
platform...) 229,472 maps when compiling `compile.dart` (from the CFE).
Thinking it was done to avoid some polymorphism I have gone over the
created flowgraphs for the file in both JIT and AOT and found only
improvements.
AOT compiled `compile.dart` then compiling itself improves by ~3.5%:
```
Difference at 95.0% confidence
-0.1365 +/- 0.0576111
-3.55191% +/- 1.49912%
(Student's t, pooled s = 0.090011)
```
Change-Id: Ifdbb57e9aa3c23b2af512a2104aaf6caf72831ef
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/301061
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>
Jens Johansen
c0c9c98787