opal/opal — pull request #375 by DouweM (2013-09-20 08:47:03+00:00)
Title: Fix Hash#has_key? to only return true for properties of its own.

Wrong:
```ruby
x = { foo: "bar" }
x.has_key?("toString") #=> true
```

Right:
```ruby
x = { foo: "bar" }
x.has_key?("toString") #=> false
```