perf(ext/web): optimize performance.measure() (#25774)

This PR optimizes the case when `performance.measure()` needs to find
the startMark by name. It is a simple change on `findMostRecent` fn to
avoiding copying and reversing the complete entries list.

Adds minor missing tests for:
- `clearMarks()`, general
- `clearMeasures()`, general
- `measure()`, case when the startMarks name exists more than once

### Benchmarks

#### main

```
    CPU | AMD Ryzen 7 PRO 6850U with Radeon Graphics
Runtime | Deno 2.0.0-rc.4 (x86_64-unknown-linux-gnu)

benchmark              time/iter (avg)        iter/s      (min … max)           p75      p99     p995
---------------------- ----------------------------- --------------------- --------------------------
worst case measure()            2.1 ms         486.9 (  1.7 ms …   2.4 ms)   2.2 ms   2.4 ms   2.4 ms
```

#### this PR

```
    CPU | AMD Ryzen 7 PRO 6850U with Radeon Graphics
Runtime | Deno 2.0.0-rc.4 (x86_64-unknown-linux-gnu)

benchmark              time/iter (avg)        iter/s      (min … max)           p75      p99     p995
---------------------- ----------------------------- --------------------- --------------------------
worst case measure()          966.3 µs         1,035 (876.9 µs …   1.1 ms)   1.0 ms   1.1 ms   1.1 ms
```

```ts
Deno.bench("worst case measure()", (b) => {
  performance.mark('start');

  for (let i = 0; i < 1e5; i += 1) {
    performance.mark(crypto.randomUUID());
  }

  b.start();

  performance.measure('total', 'start');

  b.end();

  performance.clearMarks();
  performance.clearMeasures();
});
```

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