Run deferred parameter validation whenever the surrounding context is
already strict, not only when a function body contains a Use Strict
Directive. Destructured parameter names are collected while parsing the
parameter list, so eval and arguments bindings in patterns otherwise
escaped the strict-mode early error for functions and methods.
Add parser coverage for sloppy destructuring remaining accepted, strict
source being rejected, and class methods applying their strict context.
The C++ parser was not rejecting duplicate parameter names across
destructuring patterns in non-simple parameter lists. For example,
`function f({ bar, ...a }, { bar, ...b }) {}` was accepted despite
being a syntax error per spec.
The existing inline duplicate check only ran for identifier parameters,
missing the case where both parameters are binding patterns. Add a
post-parse pass that collects all bound names and checks for duplicates
when the parameter list is non-simple (or in strict mode/arrows).
Also fix existing tests that relied on the incorrect behavior and add
new test coverage for destructuring duplicate detection.
