[gxml] Fixed GCharacterData's implementation of DomCharacterData.replace_data()

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 165c7e562e223f86b64b60e3a811fbf87f597cba
Author: Daniel Espinosa <esodan gmail com>
Date:   Thu Jul 21 19:11:45 2016 -0500

    Fixed GCharacterData's implementation of DomCharacterData.replace_data()

 gxml/DomCharacter.vala     |   10 +++-------
 test/DomGDocumentTest.vala |    6 ++++++
 2 files changed, 9 insertions(+), 7 deletions(-)
---
diff --git a/gxml/DomCharacter.vala b/gxml/DomCharacter.vala
index 284d56a..f6ba13a 100644
--- a/gxml/DomCharacter.vala
+++ b/gxml/DomCharacter.vala
@@ -55,13 +55,9 @@ public interface GXml.DomCharacterData : GLib.Object,
   public new virtual void replace_data (ulong offset, ulong count, string data) throws GLib.Error {
     if (((int)offset) > this.data.length)
       throw new DomError.INDEX_SIZE_ERROR (_("Invalid offset for replace data"));
-    int c = (int) count;
-    if (((int)offset + c) > data.length) c = data.length - (int)offset;
-
-    string s = this.data[0:(int)offset];
-    string s2 = this.data[0:(s.length - (int)offset - c)];
-    string sr = data[0:(int)count];
-    this.data = (s+sr+s2).dup ();
+    int end = (int) (offset + count);
+    if (!(end < this.data.length)) end = this.data.length;
+    this.data = this.data.splice ((int) offset, end, data);
   }
 }
 
diff --git a/test/DomGDocumentTest.vala b/test/DomGDocumentTest.vala
index da129cc..48e3264 100644
--- a/test/DomGDocumentTest.vala
+++ b/test/DomGDocumentTest.vala
@@ -498,6 +498,12 @@ static const string XMLDOC ="<?xml version=\"1.0\"?>
                                        assert_not_reached ();
                                }
                                catch {}
+                               t.append_data (" HI");
+                               assert (t.data == "TEXT HI");
+                               GLib.message ("t = "+t.substring_data (0, 4));
+                               t.replace_data (0, 4, "");
+                               GLib.message ("Text:'"+t.data+"'");
+                               assert (t.data == " HI");
                        } catch (GLib.Error e) {
                                GLib.message ("Error: "+ e.message);
                                assert_not_reached ();