Fix two bugs in LiveRange::SplitAt:

src/lithium-allocator.cc

Index: src/lithium-allocator.cc
diff --git a/src/lithium-allocator.cc b/src/lithium-allocator.cc
index 50ed122784ebda46e9ff90ba3d204bb2eff415d0..c39d5998a1a62365bbabbd6cd8c32d738d842b32 100644
--- a/src/lithium-allocator.cc
+++ b/src/lithium-allocator.cc
@@ -303,6 +303,11 @@ void LiveRange::SplitAt(LifetimePosition position, LiveRange* result) {
   // we need to split use positons in a special way.
   bool split_at_start = false;
 
+  if (current->start().Value() == position.Value()) {
+    // When splitting at start we need to locate the previous use interval.
+    current = first_interval_;
+  }
+
   while (current != NULL) {
     if (current->Contains(position)) {
       current->SplitAt(position);
@@ -352,6 +357,11 @@ void LiveRange::SplitAt(LifetimePosition position, LiveRange* result) {
   }
   result->first_pos_ = use_after;
 
+  // Discard cached iteration state. It might be pointing
+  // to the use that no longer belongs to this live range.
+  last_processed_use_ = NULL;
+  current_interval_ = NULL;
+
   // Link the new live range in the chain before any of the other
   // ranges linked from the range before the split.
   result->parent_ = (parent_ == NULL) ? this : parent_;