fix(javascript): yield during the largest AST traversals (#1545)

After #1542 the longest event-loop blocks on large bundles were single AST
traversals inside one analyzer: member-mutation collection with its
fixpoint, static source analysis, and function fingerprints, each about
one second on Obsidian's 3.7 MB app.js.

- traverseJavaScriptAstSteps yields every 1,024 visited nodes with the
  same visit order; traverseJavaScriptAst drains it, so every existing
  caller is unchanged.
- Member mutations, static analysis and fingerprints run as steps. The
  member-mutation fixpoint yields every 64 references, and fingerprints
  yield between callables.
- The now-unused synchronous member-mutation and fingerprint wrappers are
  removed.

Graph IDs and complete result digests match main on three inputs,
including obsidian.asar. Over two runs there, the longest block falls
from about 920 ms to 740 ms, the second from 860 to 595 ms, and blocks
over 250 ms from 27 to 18, with total time within 1.5%.

Refs #1462

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/domain/javascript/javascriptSemanticMemberMutations.ts

@@ -25,7 +25,7 @@ import {
   type JavaScriptSemanticPropertyPath,
 } from "./javascriptSemanticPropertyPaths.js";
 import { compareUnicodeCodePoints } from "../unicodeCodePointOrder.js";
-import { traverseJavaScriptAst } from "./javascriptSemanticTraversal.js";
+import { traverseJavaScriptAstSteps } from "./javascriptSemanticTraversal.js";
 import {
   semanticStaticPropertyKey,
   unwrapJavaScriptExpression,
@@ -34,13 +34,13 @@ import {
 type PropertyPath = JavaScriptSemanticPropertyPath;
 type ValueEffect = "write" | "escape";
 
-/** Preserve uncertainty from property writes and references exposed to calls. */
-export const collectSemanticMemberMutations = (
+/** Preserve uncertainty from property writes and references exposed to calls, yielding during traversal and fixpoint iteration. */
+export function* collectSemanticMemberMutationsSteps(
   program: t.Program,
   state: JavaScriptSemanticAnalysisState,
-): void => {
+): Generator<void, void> {
   const parents = state.parentsByNode;
-  traverseJavaScriptAst(program, {
+  yield* traverseJavaScriptAstSteps(program, {
     enter: (node, parent) => {
       if (parent !== null) parents.set(node, parent);
     },
@@ -382,7 +382,7 @@ export const collectSemanticMemberMutations = (
         );
     }
   };
-  traverseJavaScriptAst(program, {
+  yield* traverseJavaScriptAstSteps(program, {
     enter: (node, parent) => {
       for (const source of semanticIterationSources(node, parent))
         deferIterable({
@@ -435,7 +435,8 @@ export const collectSemanticMemberMutations = (
     const effectsBefore = recordedEffects.size;
     const iterablesBefore = iterableReferences.length;
     const iterationBefore: boolean = arrayIterationUnknown;
-    for (const reference of pendingReferences.splice(0)) {
+    for (const [index, reference] of pendingReferences.splice(0).entries()) {
+      if (index % 64 === 0) yield;
       const { initializer } = reference;
       if (referenceSourcesInactive(initializer, state))
         pendingReferences.push(reference);
@@ -480,7 +481,8 @@ export const collectSemanticMemberMutations = (
           reference.originAt,
         );
     }
-    for (const reference of [...iterableReferences]) {
+    for (const [index, reference] of [...iterableReferences].entries()) {
+      if (index % 64 === 0) yield;
       if (referenceSourcesInactive(reference, state)) continue;
       if (reference.iterationOnly) {
         const expanded = expandedIterationReferences(reference, state);
@@ -518,7 +520,7 @@ export const collectSemanticMemberMutations = (
   // Gathering effects can evaluate a primitive projection before its object
   // escapes. Final values must use the completed mutation state.
   clearSemanticPrimitiveBindingValues(state);
-};
+}
 
 interface ReferencedValue {
   readonly node: t.Node;