fix: report a missing class name as a syntax error

[marevol]

Stacked on #53.

A class declaration with no name did not produce a SyntaxError:

class {}      no message resource found for message id: parser.error.expected.ident
class 1 {}    same

className() asked for the message key parser.error.expected.ident, which does not exist. ECMAErrors.getMessage turns the MissingResourceException into a plain RuntimeException, so the error was neither a ParserException nor — under JSR-223 — a ScriptException.

Fix

There is no need for a new key: this is the same "Expected X but found Y" that expectDontAdvance reports everywhere else, so className() now builds it the same way, through the existing expected key. That also fixes the argument, which named the token being looked at rather than the one that was wrong — the message said class where the offending token was {.

class {}      Expected ident but found {
class 1 {}    Expected ident but found 1

Two error tests come with it. Neither a malformed class name nor a duplicated constructor had one, which is why a message key that never resolved could ship. The duplicate-constructor message was already correct and is now covered.

Verification

./gradlew build testOptimistic testPessimistic

suite	before	after
test	665, 0 fail	665, 0 fail
testOptimistic	1715, 0 fail	1717, 0 fail
testPessimistic	1715, 0 fail	1717, 0 fail