Fix fix interop block argument passing test and docs.

Author: aardvark179

doc/contributor/interop_implicit_api.md

@@ -24,7 +24,7 @@ Format: `Ruby code` sends `InteropLibrary message`
 - `foreign_object.method_name` sends `readMember(foreign_object, method_name)` if member is readable
 - `foreign_object.method_name` sends `readMember(foreign_object, method_name)` and raises if member is not invocable or readable
 - `foreign_object.method_name(*arguments)` sends `invokeMember(foreign_object, method_name, *arguments)` if member is readable and invokable
-- `foreign_object.method_name(*arguments) &block` sends `invokeMember(foreign_object, method_name, *arguments, block)`
+- `foreign_object.method_name(*arguments, &block)` sends `invokeMember(foreign_object, method_name, *arguments, block)`
 - `foreign_object.new(*arguments)` sends `instantiate(foreign_object, *arguments)`
 - `foreign_object.class` sends `readMember(foreign_object, "class")` when `foreign_object` is a `java.lang.Class`
 - `foreign_object.class` sends `getMetaObject(foreign_object)`

spec/truffle/interop/special_forms_spec.rb

@@ -173,7 +173,7 @@
     l.log.should include(["invokeMember", "bar", 1, 2, 3])
   end
 
-  it description['.method_name(*arguments) &block', :invokeMember, ['method_name', '*arguments, block']] do
+  it description['.method_name(*arguments, &block)', :invokeMember, ['method_name', '*arguments, block']] do
     pfo, pm, l = proxy[TruffleInteropSpecs::PolyglotMember.new]
     block = Proc.new {}
     pfo.foo = -> *x { 1 }