Reduce allocations for getStackLineInfo + getStackAddressInfo

[mstange]

Production | Deploy preview

On large profiles, opening the source view can cause large allocations because we create Set objects for many stacks. In this PR I've experimented with a more compact storage of a collection of sets.

Before: https://share.firefox.dev/3NnthpO
After: https://share.firefox.dev/45dMNv1

getStackLineInfo now allocates 46MB instead of 220MB (4.8x reduction), and takes 146ms instead of 338ms (2.3x reduction), when opening the source view for mozjemalloc.cpp on https://share.firefox.dev/3NnzEcF.

To do:

• Add tests for intset-table.ts
• Add comments to intset-table.ts
• Rewrite comments above getStackLineInfo and getStackAddressInfo
• Wait for Fix "scroll to hotspot" functionality in the source view + assembly view #5759 to land first

[codecov]

Codecov Report

❌ Patch coverage is 84.01937% with 66 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.60%. Comparing base (0dd124f) to head (3c99ec6).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/profile-logic/bottom-box.ts	65.30%	17 Missing ⚠️
src/utils/bitset.ts	0.00%	13 Missing ⚠️
...mponents/app/AssemblyViewNativeSymbolNavigator.tsx	42.10%	11 Missing ⚠️
src/utils/intset-table.ts	90.80%	8 Missing ⚠️
src/components/shared/AssemblyView-codemirror.tsx	50.00%	6 Missing ⚠️
src/components/shared/AssemblyView.tsx	66.66%	3 Missing ⚠️
src/actions/profile-view.ts	71.42%	2 Missing ⚠️
src/reducers/url-state.ts	83.33%	2 Missing ⚠️
src/components/shared/SourceView.tsx	0.00%	1 Missing ⚠️
src/profile-logic/address-timings.ts	98.21%	1 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5761      +/-   ##
==========================================
- Coverage   85.67%   85.60%   -0.07%     
==========================================
  Files         315      318       +3     
  Lines       31110    31256     +146     
  Branches     8472     8612     +140     
==========================================
+ Hits        26654    26758     +104     
- Misses       4026     4068      +42     
  Partials      430      430              

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