[vm] Cleanup unused BoolField

TEST=ci

Change-Id: I0dfe936bf9b1bb1600fdb740b2dda4989745ef06
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/402121
Reviewed-by: Alexander Aprelev <[email protected]>
Commit-Queue: Alexander Markov <[email protected]>

Author: alexmarkov

runtime/vm/boolfield.h

@@ -16,7 +16,6 @@ vm_sources = [
   "bitfield.h",
   "bitmap.cc",
   "bitmap.h",
-  "boolfield.h",
   "bootstrap.h",
   "bootstrap_natives.cc",
   "bootstrap_natives.h",
@@ -379,7 +378,6 @@ vm_sources_tests = [
   "bit_vector_test.cc",
   "bitfield_test.cc",
   "bitmap_test.cc",
-  "boolfield_test.cc",
   "catch_entry_moves_test.cc",
   "class_finalizer_test.cc",
   "code_descriptors_test.cc",