XS: Math.atan2 and Math.pow skip coercing the first argument when the second argument is omitted

[d01c2]

Build environment: macOS 26.5.2

Moddable SDK version:

• Installed via jsvu, so there is no SDK source tree / git describe.
• Engine reports: XS 17.9.1, slot 32 bytes, ID 4 bytes

Target device: desktop (host xs)

Description
Math.atan2 and Math.pow return NaN without coercing the first argument when the second argument is omitted.

Both algorithms apply ToNumber to the first argument before applying it to the second argument. Since applying ToNumber to a BigInt throws a TypeError, both calls should throw before processing the omitted second argument.

Steps to Reproduce

$ xst -e 'print("atan2: " + String(Math.atan2(0n))); print("pow: " + String(Math.pow(0n)))'
atan2: NaN
pow: NaN

Expected behavior
Both calls throw a TypeError.

For comparison, V8 (15.3.27):

$ v8 -e 'for (const name of ["atan2", "pow"]) { try { Math[name](0n); } catch (e) { print(name + ": " + e.name); } }'
atan2: TypeError
pow: TypeError

Other information
XS throws the expected errors when the second argument is explicitly supplied as undefined:

$ xst -e 'for (const name of ["atan2", "pow"]) { try { Math[name](0n, undefined); } catch (e) { print(name + ": " + e.name); } }'
atan2: TypeError
pow: TypeError