Add specs for `/regexp/ =~ "string" sets local variables`
Tag failing new specs for `/regexp/ =~ "string" sets local variables`
Remove calls to removed function rb_str_flush
Remove unused ValueGenerator from Array
Merge pull request #2469 from kachick/spec-regexp-named_capture_sets_local-var

Add specs for `/regexp/ =~ "string"` with named captures should set local variables
Always check for local reference first when sending

The handling of a Regexp =~ local means we should check here if there is
a local before emitting a send. This is the easiest solution, otherwise
the parser would have been told about this knowledge.
Setup locals from Regexp =~

Fixes #2051 and #2466
Remove tags for now passing specs
Write specs for StopIteration#result

[1.9.1](https://github.com/ruby/ruby/blob/1306ae8a461b30fbc59aedea7262958cc5775137/enumerator.c#L792)
[1.9.2](https://github.com/ruby/ruby/blob/e80d0a9631cdfebc53c1a111eb2162fe3f1dc67c/enumerator.c#L1097-L1098)
Implement StopIteration#result