Add float version of gfx::Range

ui/gfx/range/range.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_RANGE_RANGE_H_
 #define UI_GFX_RANGE_RANGE_H_
 
 #include <ostream>
 #include <string>
 
@@ skipping 36 matching lines @@
   explicit Range(const NSRange& range);
 #elif defined(OS_WIN)
   // The |total_length| paramater should be used if the CHARRANGE is set to
   // {0,-1} to indicate the whole range.
   Range(const CHARRANGE& range, LONG total_length = -1);
 #endif
 
   // Returns a range that is invalid, which is {size_t_max,size_t_max}.
   static const Range InvalidRange();
 
-  // Checks if the range is valid through comparision to InvalidRange().
+  // Checks if the range is valid through comparison to InvalidRange().
   bool IsValid() const;
 
   // Getters and setters.
   size_t start() const { return start_; }
   void set_start(size_t start) { start_ = start; }
 
   size_t end() const { return end_; }
   void set_end(size_t end) { end_ = end; }
 
   // Returns the absolute value of the length.
@@ skipping 40 matching lines @@
  private:
   size_t start_;
   size_t end_;
 };
 
 GFX_EXPORT std::ostream& operator<<(std::ostream& os, const Range& range);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RANGE_RANGE_H_