fix(wpt): improve harness compatibility

[nabetti1720]

Issue # (if available)

n/a

Description of changes

Improve WPT harness compatibility with LLRT's server-side runtime.

• Provide browser-like self, console, and DOMException globals.
• Add runtime global fallback for WPT contexts.
• Support self.location and relative URL resolution in Fetch tests.

Checklist

• Created unit tests in tests/unit and/or in Rust for my feature if needed
• Ran make fix to format JS and apply Clippy auto fixes
• Made sure my code didn't add any additional warnings: make check
• Added relevant type info in types/ directory
• Updated documentation if needed (API.md/README.md/Other)

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[richarddd]

@nabetti1720 this is a bit out of scope for this PR but the hole point of wpt-errors is to keep track of what's supported and whats not. Now that we discard unsupported behaviour via filters in wpt-harness we no longer see that. I suggest we remove the filter and just maintain the wpt-errors.txt file.

[nabetti1720]

@nabetti1720 this is a bit out of scope for this PR but the hole point of wpt-errors is to keep track of what's supported and whats not. Now that we discard unsupported behaviour via filters in wpt-harness we no longer see that. I suggest we remove the filter and just maintain the wpt-errors.txt file.

I excluded that test, deeming it meaningless in a server-side runtime environment. However, there is value in keeping it as an error precisely to make that point clear.

The remaining fix concerns the harness mismatch. Resolving this cleared up the strange errors and revealed new errors specific to the test cases themselves.