Remove errant check for kw args which are now universally supported

spec/rspec/mocks/partial_double_spec.rb

@@ -81,15 +81,10 @@ def call(name)
         expect(object.foobar(:key => "value")).to equal(1)
       end
 
-      if RSpec::Support::RubyFeatures.required_kw_args_supported?
-        # Use eval to avoid syntax error on 1.8 and 1.9
-        binding.eval(<<-CODE, __FILE__, __LINE__)
-        it "can accept an inner hash as a message argument" do
-          hash = {:a => {:key => "value"}}
-          expect(object).to receive(:foobar).with(:key => "value").and_return(1)
-          expect(object.foobar(**hash[:a])).to equal(1)
-        end
-        CODE
+      it "can accept an inner hash as a message argument" do
+        hash = {:a => {:key => "value"}}
+        expect(object).to receive(:foobar).with(:key => "value").and_return(1)
+        expect(object.foobar(**hash[:a])).to equal(1)
       end
 
       it "can create a positive message expectation" do