Fix issue with rendering partials and then yielding inside a render layout call

The given block was never being executed when another render :partial call
existed before the yield call, due to the block being overriden.

This commit also adds some more tests to render with :layout option.

actionpack/test/fixtures/layouts/_partial_and_yield.erb

@@ -0,0 +1,2 @@
+<%= render :partial => 'test/partial' %>
+<%= yield %>

actionpack/test/fixtures/layouts/_yield_only.erb

@@ -0,0 +1 @@
+<%= yield %>

actionpack/test/fixtures/layouts/_yield_with_params.erb

@@ -0,0 +1 @@
+<%= yield 'Yield!' %>

actionpack/test/fixtures/layouts/yield_with_render_partial_inside.erb

@@ -0,0 +1,2 @@
+<%= render :partial => 'test/partial' %>
+<%= yield %>

actionpack/test/template/render_test.rb

@@ -247,6 +247,26 @@ module RenderTestCases
       @view.render(:file => "test/hello_world.erb", :layout => "layouts/yield_with_render_inline_inside")
   end
 
+  def test_render_with_layout_which_renders_another_partial
+    assert_equal %(partial html\nHello world!\n),
+      @view.render(:file => "test/hello_world.erb", :layout => "layouts/yield_with_render_partial_inside")
+  end
+
+  def test_render_layout_with_block_and_yield
+    assert_equal %(Content from block!\n),
+      @view.render(:layout => "layouts/yield_only") { "Content from block!" }
+  end
+
+  def test_render_layout_with_block_and_yield_with_params
+    assert_equal %(Yield! Content from block!\n),
+      @view.render(:layout => "layouts/yield_with_params") { |param| "#{param} Content from block!" }
+  end
+
+  def test_render_layout_with_block_which_renders_another_partial_and_yields
+    assert_equal %(partial html\nContent from block!\n),
+      @view.render(:layout => "layouts/partial_and_yield") { "Content from block!" }
+  end
+
   def test_render_with_nested_layout
     assert_equal %(<title>title</title>\n\n<div id="column">column</div>\n<div id="content">content</div>\n),
       @view.render(:file => "test/nested_layout.erb", :layout => "layouts/yield")