Perform simple type inference in the editor

[DartBot]

This issue was originally filed by [email protected]

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Consider the following code:

doSomething(var x) {
  if (x is MyObject) {
    // blah blah blah
  } else {
    // other stuff
  }
}

When entering 'x.' within the 'x is MyObject' clause, it would great if method autocompletion would take the type of x to be 'MyObject' rather than giving up and saying 'No completions available.'

I don't expect global type inference at this point, but a simple local check of the enclosing scope would be a big help.

[stevemessick]

That's a good idea. Another improvement would be to do Smalltalk-style suggestions. That is, find all methods that match the prefix that was typed and propose them as completions. It doesn't use types at all, and is more useful when you've typed something like "x.get" followed by Ctrl-Space. Paying attention to final var decls that have a well-typed RHS would also be good.

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Set owner to @stevemessick.

[stevemessick]

Added Started label.

[clayberg]

Removed Type-Defect label.
Added Type-Enhancement, Duplicate labels.
Marked as being merged into #508.

[clayberg]

Marked as being merged into #dart:502.