Remove JRuby and 1.8 workarounds

Author: pirj

spec/rspec/mocks/partial_double_spec.rb

@@ -184,7 +184,7 @@ def expect_output_warning_on_ruby_lt_2
         yield
       end
 
-      it "allows `write` to be stubbed and reset", :unless => Support::Ruby.jruby? do
+      it "allows `write` to be stubbed and reset" do
         allow(file_1).to receive(:write)
         file_1.reopen(file_2)
         expect_output_warning_on_ruby_lt_2 { reset file_1 }
@@ -197,7 +197,7 @@ def expect_output_warning_on_ruby_lt_2
       end
     end
 
-    RSpec.describe "Using a partial mock on a proxy object", :if => defined?(::BasicObject) do
+    RSpec.describe "Using a partial mock on a proxy object" do
       let(:proxy_class) do
         Class.new(::BasicObject) do
           def initialize(target)