[trestoncuzzort]

Fixes #1796.

Check IsRegExp and the global flag before reading Symbol.matchAll. Implement the RegExpCreate fallback in match, search and matchAll by converting and compiling the pattern directly, avoiding extra Symbol.match and source reads and honoring an overridden RegExp toString().

The regression covers getter order, changing flags, custom matcher receivers, pattern conversion and exceptions. Three groups fail on the original engine; all four pass after the fix.

Validation against the exact base and submitted revisions:

• Linux GCC 16: all 121 local files pass, nine excluded. Full pinned test262: both revisions retain 40 known failures across 82,220 tests, with no expectation changes.
• Windows MSVC x64: full local suite, C API tests, all 119 relevant conformance cases and original/fixed regression controls pass. The initial harness used an unsuitable absolute module path; the follow-up changes only its invocation directory.
• macOS Clang ASan/UBSan: regression controls, C API tests and all 119 relevant cases pass. Full test262 retains the same 40 known failures across 82,220 tests on both revisions, with expectations unchanged.

Known baseline failure: the full sanitizer local suite has the same test_std.js second-pipe-handler assertion on both revisions, on Linux and macOS. Its runner exits zero despite that assertion; the counts and diagnostics were checked directly. The new regression passes under sanitizers. Full Windows test262 and full Linux sanitizer test262 were not run.

Implemented and tested with Codex assistance.