fix(selfhost/parser): skip newlines inside expressions

The selfhost parser did not skip tkNewLine tokens inside expression parsing,
causing multi-line expressions (e.g. if conditions spanning lines with ||)
to be truncated. When parserParseBinaryPrec hit a newline it treated it as
an invalid primary, returning a malformed literal and leaving p.pos at the
newline. parserParseBlock then failed to find '{' and its depth-counter
fallback consumed far too many tokens, causing subsequent function bodies
to be parsed into the wrong AST nodes.

Fix: add newline skipping in parserParsePrimary, parserParseUnary, and
parserParseBinaryPrec, matching the bootstrap parser's skipNewlines() calls
in parseAnd/parseOr.

Also complete the variant cap raise from 8->9 in src/sema.bux (was already
done in ast.bux, parser.bux, hir_lower.bux).

src/ast.bux

@@ -265,6 +265,7 @@ struct Decl {
     variant5: EnumVariant,
     variant6: EnumVariant,
     variant7: EnumVariant,
+    variant8: EnumVariant,
     // Impl methods (up to 4)
     methodCount: int,
     // Use/import