Merge 88139

Source/WebCore/platform/graphics/TextRun.h

Index: Source/WebCore/platform/graphics/TextRun.h
===================================================================
--- Source/WebCore/platform/graphics/TextRun.h	(revision 88778)
+++ Source/WebCore/platform/graphics/TextRun.h	(working copy)
@@ -78,8 +78,8 @@
     {
     }
 
-    UChar operator[](int i) const { return m_characters[i]; }
-    const UChar* data(int i) const { return &m_characters[i]; }
+    UChar operator[](int i) const { ASSERT(i >= 0 && i < m_len); return m_characters[i]; }
+    const UChar* data(int i) const { ASSERT(i >= 0 && i < m_len); return &m_characters[i]; }
 
     const UChar* characters() const { return m_characters; }
     int length() const { return m_len; }