Align this PR with specify_null_safety_sep21

Author: eernstg

specification/dartLangSpec.tex

@@ -24,13 +24,7 @@
 % CHANGES
 % =======
 %
-% Significant changes to the specification. Note that the versions specified
-% below indicate the current tool chain version when those changes were made.
-% In practice, new features have always been integrated into the language
-% specification (this document) a while after the change was accepted into
-% the language and implemented. As of September 2022, the upcoming version of
-% the language which is being specified is indicated by a version number in
-% parentheses after the tool chain version.
+% Significant changes to the specification.
 %
 % Note that the version numbers used below (up to 2.15) were associated with
 % the currently released language and tools at the time of the spec change,
@@ -44,6 +38,8 @@
 % Jul 2025
 % - Clarify that operator `[]` and `[]=` are included in the `void` allowlist
 %   rule about formal parameters of type `void`, and so are setters.
+% - Integrate the subtyping rule updates that are needed in order to support
+%   null-safety.
 %
 % May 2025
 % - Add `s?.length` as a constant expression in the case where `s` satisfies
@@ -76,8 +72,6 @@
 %   a function literal.
 % - Specify in which situations it is an error to declare an initializing
 %   formal parameter.
-% - Integrate the subtyping rule updates that are needed in order to support
-%   null-safety.
 %
 % Nov 2023
 % - Specify that the dynamic error for calling a function in a deferred and