Remove unused classifiable name tracking

[jakebailey]

goos: linux
goarch: amd64
pkg: github.com/microsoft/typescript-go/internal/binder
cpu: AMD Ryzen AI 9 HX 370 w/ Radeon 890M           
                                                     │   old.txt   │              new.txt               │
                                                     │   sec/op    │   sec/op     vs base               │
Bind/empty.ts-24                                       111.0n ± 3%   111.8n ± 1%       ~ (p=0.517 n=10)
Bind/checker.ts-24                                     10.14m ± 2%   10.09m ± 1%  -0.50% (p=0.023 n=10)
Bind/dom.generated.d.ts-24                             3.617m ± 1%   3.440m ± 1%  -4.90% (p=0.000 n=10)
Bind/Herebyfile.mjs-24                                 178.2µ ± 1%   178.9µ ± 1%       ~ (p=0.436 n=10)
Bind/jsxComplexSignatureHasApplicabilityError.tsx-24   63.24µ ± 1%   61.63µ ± 1%  -2.55% (p=0.000 n=10)
geomean                                                135.6µ        133.7µ       -1.41%

                                                     │   old.txt    │                new.txt                │
                                                     │     B/op     │     B/op      vs base                 │
Bind/empty.ts-24                                         64.00 ± 0%     64.00 ± 0%       ~ (p=1.000 n=10) ¹
Bind/checker.ts-24                                     7.184Mi ± 0%   7.080Mi ± 0%  -1.45% (p=0.000 n=10)
Bind/dom.generated.d.ts-24                             5.232Mi ± 0%   5.041Mi ± 0%  -3.64% (p=0.000 n=10)
Bind/Herebyfile.mjs-24                                 164.1Ki ± 0%   160.8Ki ± 0%  -2.06% (p=0.000 n=10)
Bind/jsxComplexSignatureHasApplicabilityError.tsx-24   108.6Ki ± 0%   105.2Ki ± 0%  -3.11% (p=0.000 n=10)
geomean                                                134.4Ki        131.7Ki       -2.06%
¹ all samples are equal

                                                     │   old.txt   │               new.txt                │
                                                     │  allocs/op  │  allocs/op   vs base                 │
Bind/empty.ts-24                                        1.000 ± 0%    1.000 ± 0%       ~ (p=1.000 n=10) ¹
Bind/checker.ts-24                                     13.97k ± 0%   13.95k ± 0%  -0.16% (p=0.000 n=10)
Bind/dom.generated.d.ts-24                             16.59k ± 0%   16.56k ± 0%  -0.17% (p=0.000 n=10)
Bind/Herebyfile.mjs-24                                  355.0 ± 0%    346.0 ± 0%  -2.54% (p=0.000 n=10)
Bind/jsxComplexSignatureHasApplicabilityError.tsx-24    278.0 ± 0%    269.0 ± 0%  -3.24% (p=0.000 n=10)
geomean                                                 469.7         464.0       -1.23%
¹ all samples are equal

[Copilot]

Pull request overview

Removes unused classifiable-name tracking to reduce binder allocations and improve performance.

Changes:

• Removes the unused per-file classifiable-name set.
• Removes binder bookkeeping for classifiable declarations.
• Removes the now-unused composite symbol flag.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
internal/binder/binder.go	Removes classifiable-name collection and assignment.
internal/ast/symbolflags.go	Removes the unused SymbolFlagsClassifiable flag.
internal/ast/ast.go	Removes SourceFile.ClassifiableNames and its unused import.