Unfortunate error recovery for final variable declaration with missing variable names

[leafpetersen]

From user feedback. Consider this code:

void test() {
  final double x;
  final double y;
  final double = 4.0;
}

The user is in the middle of editing or adding the variable name for the last line (or has forgotten to add the variable), but the error messages they see are the following:

[error] Local variable 'double' can't be referenced before it is declared. (/Users/leafp/tmp/test.dart, line 2, col 9)
[error] Local variable 'double' can't be referenced before it is declared. (/Users/leafp/tmp/test.dart, line 3, col 9)

This is confusing, and with lots of these variables in scope, the error messages are very noisy in the interim (even if the user correctly identifies the problem).

I wonder if at least in the IDE, errors that arise from using a local variable as a type could be recognized, collapsed, and a hint generated pointing to the place where the "type as local variable" is declared? Perhaps only doing this when the local variable is a type name in the enclosing scope?

cc @Hixie