[parser] Support BigIntLiteral in visitMemberKey

[CSharperMantle]

Currently, when trying to parse the following program using parser.js:

({1n: 0});
class C { 1n(){} }
for (const {1n: x} of [{}]) {}

... this exception is thrown:

$ node parser.js ../../Protobuf/ast.proto /tmp/demo.js /dev/null

/home/csmantle/workspace/fuzzilli/Sources/Fuzzilli/Compiler/Parser/parser.js:263
                throw "Unknown member key type: " + member.key.type + " in declaration";
                ^
Unknown member key type: BigIntLiteral in declaration
(Use `node --trace-uncaught ...` to show where the exception was thrown)

Node.js v26.8.2

Similar BigInt-keyed patterns are also found in SpiderMonkey's js/src/jit-test/tests/1659595.js.

visitExpression in parser.js already handles the BigIntLiteral type; thus, fix up the visitMemberKey handling similarly.

fuzzilli/Sources/Fuzzilli/Compiler/Parser/parser.js

Lines 618 to 620 in e2f6fa7

	case 'BigIntLiteral': {
	return makeExpression('BigIntLiteral', { value: node.value });
	}

This fix would enable correct parsing of all three patterns mentioned above.

[Liedtke]

LGTM, thanks a lot!