Eliot Miranda uploaded a new version of Kernel to project The Trunk:
http://source.squeak.org/trunk/Kernel-eem.1108.mcz

==================== Summary ====================

Name: Kernel-eem.1108
Author: eem
Time: 23 June 2017, 11:35:28.572002 am
UUID: dd3439ca-404b-4d0d-bb11-529ed86a96eb
Ancestors: Kernel-nice.1107

Implement messagesDo: using ifAbsentAdd:

=============== Diff against Kernel-nice.1107 ===============

Item was changed:
  ----- Method: CompiledMethod>>messagesDo: (in category 'scanning') -----
  messagesDo: aBlock
  	"Evaluate aBlock exactly once with all the message selectors sent by me."
  
  	| scanner aSet |
  	self isQuick ifTrue: [ ^self ].
- 	aSet := nil.
  	scanner := InstructionStream on: self.
  	scanner scanFor: [ :x |
  		| selector |
  		(selector := scanner selectorToSendOrSelf) == scanner ifFalse: [
+ 			((aSet ifNil: [ aSet := IdentitySet new ]) ifAbsentAdd: selector) ifTrue: [
- 			((aSet ifNil: [ aSet := IdentitySet new ]) addNewElement: selector) ifTrue: [
  				aBlock value: selector ] ].
  		false "keep scanning" ]!