Suppress error highlight for some incomplete code

[tompng]

It is better to not render class with RED-REVERSE color. Filter specific errors if error location is at the last non-newline non-comment token position.

class was rendered RED-REVERSE, will be rendered GREEN
class; will be rendered RED-REVESE as before

Detail

Many errors at the end should be highlighted

• def f.@invalid_method_name
• 1@a
• :123
• tap do end end

Only a few error types at the end should be filtered out

• class
• class a (followed by ::A is valid)
• a,b (followed by =c is valid)
• [*
• f(**
• f(&
• def f =
• =begin

Some patterns aren't possible to handle with the approach in this pull request

• def $a (followed by .f is valid)
• def $a.$a (invalid, same error will be raised)
• *, (followed by a=b is valid, but error location is not at the end)