Add iterator support to DWARFDie to allow child DIE iteration.

Differential Revision: https://reviews.llvm.org/D28303

llvm-svn: 291194
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
index deec163..2aac347 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
@@ -299,11 +299,8 @@
     Ranges.insert(Ranges.end(), DIERanges.begin(), DIERanges.end());
   }
 
-  DWARFDie Child = getFirstChild();
-  while (Child) {
+  for (auto Child: children())
     Child.collectChildrenAddressRanges(Ranges);
-    Child = Child.getSibling();
-  }
 }
 
 bool DWARFDie::addressRangeContainsAddress(const uint64_t Address) const {