Add float version of gfx::Range

ui/gfx/render_text_unittest.cc

Index: ui/gfx/render_text_unittest.cc
diff --git a/ui/gfx/render_text_unittest.cc b/ui/gfx/render_text_unittest.cc
index 7baa201c195b3632878fd631d4f357fbf4c04d3c..4b2133340eaa554ede05e363389501eeeaca1584 100644
--- a/ui/gfx/render_text_unittest.cc
+++ b/ui/gfx/render_text_unittest.cc
@@ -2161,7 +2161,7 @@ TEST_F(RenderTextTest, HarfBuzz_SubglyphGraphemeCases) {
     auto first_grapheme_bounds = run->GetGraphemeBounds(iter, 0);
     EXPECT_EQ(first_grapheme_bounds, run->GetGraphemeBounds(iter, 1));
     auto second_grapheme_bounds = run->GetGraphemeBounds(iter, 2);
-    EXPECT_EQ(first_grapheme_bounds.second, second_grapheme_bounds.first);
+    EXPECT_EQ(first_grapheme_bounds.end(), second_grapheme_bounds.start());
   }
 }