url: speed up WHATWG URL parsing

[anonrig]

Speeds up new URL() / URL.parse() on the common path: already-serialized ASCII hrefs.

The binding currently always:

1. Copies the V8 string into a UTF-8 buffer (Utf8Value)
2. Parses with Ada
3. Allocates a new V8 string from href, even when it is byte-identical to the input

Typical URLs (https://example.com/path, the whatwg-url-parse benchmark corpus) are one-byte ASCII and already in serialized form. This change:

• Parses one-byte ASCII inputs in place via v8::String::ValueView (no UTF-8 copy)
• Returns the original V8 string when href == input (no second string allocation)
• Avoids copying the base URL into a temporary std::string just to parse it
• Applies the same in-place parse to update() (setters re-parse an already-serialized href)
• Delays URLContext allocation until parse finishes, and initializes it in one shot from urlComponents
• Skips `${input}` when the value is already a string

Non-ASCII inputs still go through Utf8Value. Those results are never reused as the original string, because UTF-8 conversion may replace unpaired surrogates.

Benchmark

Same machine, Release build, benchmark/url/whatwg-url-parse.js e=12. Repeated runs:

Config	Before (ops/s)	After (ops/s)	Change
short / no base	7.82M	9.29M	+19%
long / no base	2.50M	2.75M	+10%
short / with base	2.94M	3.39M	+15%

dot (needs path normalization, so a new href string) is unchanged.

Tests

• test/parallel/test-whatwg-url-*.js and test-url-*.js: 54 pass, 1 skip
• WPT url: 5107 pass, 0 unexpected failures
• New test/parallel/test-whatwg-url-parse-fast-path.js covers already-serialized ASCII hrefs, trailing-slash and dot-segment normalization, base resolution, non-string input, invalid input, unpaired surrogates, IDN, and setters

Assisted-by: Cursor

[nodejs-github-bot]

Review requested:

• @nodejs/url

[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.13%. Comparing base (13fcd6f) to head (fa5ca3f).
⚠️ Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_url.cc	93.47%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65361      +/-   ##
==========================================
- Coverage   91.85%   90.13%   -1.73%     
==========================================
  Files         400      752     +352     
  Lines      178855   251898   +73043     
  Branches    27319    47378   +20059     
==========================================
+ Hits       164283   227037   +62754     
- Misses      14243    16185    +1942     
- Partials      329     8676    +8347     

Files with missing lines	Coverage Δ
lib/internal/url.js	93.28% <100.00%> (+13.12%)	⬆️
src/node_url.cc	79.30% <93.47%> (ø)

... and 482 files with indirect coverage changes

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[jasnell]

AI agents are not permitted to Signed-off-by

[mcollina]

lgtm

[anonrig]

Removed the Signed-off-by trailer from the commit(s). An AI agent cannot attest the DCO.