Simplify and rename IsLoopInvariant() test.

Simplify IsLoopInvariant() test. Also rename it to IsDefinedOutOfTheLoop()
so there is no ambiguity for example whether a instruction after the loop counts
as a loop invariant. It's up to the caller to make the interpretation.

Change-Id: I999139032b0e4d815dd1e2276f2bd428cf558686
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index 9b26de4..461be25 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -587,15 +587,8 @@
   return other.blocks_.IsBitSet(header_->GetBlockId());
 }
 
-bool HLoopInformation::IsLoopInvariant(HInstruction* instruction, bool must_dominate) const {
-  HLoopInformation* other_loop = instruction->GetBlock()->GetLoopInformation();
-  if (other_loop != this && (other_loop == nullptr || !other_loop->IsIn(*this))) {
-    if (must_dominate) {
-      return instruction->GetBlock()->Dominates(GetHeader());
-    }
-    return true;
-  }
-  return false;
+bool HLoopInformation::IsDefinedOutOfTheLoop(HInstruction* instruction) const {
+  return !blocks_.IsBitSet(instruction->GetBlock()->GetBlockId());
 }
 
 size_t HLoopInformation::GetLifetimeEnd() const {