Revert of [turbofan] simplify gap ordering

test/unittests/compiler/move-optimizer-unittest.cc

Index: test/unittests/compiler/move-optimizer-unittest.cc
diff --git a/test/unittests/compiler/move-optimizer-unittest.cc b/test/unittests/compiler/move-optimizer-unittest.cc
index 2452d19914da05f0c5eaf82ad28dc0373a24709d..5b956f077a9657821f21b2aa5e1614ae249f8781 100644
--- a/test/unittests/compiler/move-optimizer-unittest.cc
+++ b/test/unittests/compiler/move-optimizer-unittest.cc
@@ -12,7 +12,11 @@
 class MoveOptimizerTest : public InstructionSequenceTest {
  public:
   GapInstruction* LastGap() {
-    return GapInstruction::cast(*(sequence()->instructions().rbegin() + 1));
+    auto instruction = sequence()->instructions().back();
+    if (!instruction->IsGapMoves()) {
+      instruction = *(sequence()->instructions().rbegin() + 1);
+    }
+    return GapInstruction::cast(instruction);
   }
 
   void AddMove(GapInstruction* gap, TestOperand from, TestOperand to,
@@ -86,10 +90,10 @@
 
 TEST_F(MoveOptimizerTest, RemovesRedundant) {
   StartBlock();
-  EmitNop();
   AddMove(LastGap(), Reg(0), Reg(1));
   EmitNop();
   AddMove(LastGap(), Reg(1), Reg(0));
+  EmitNop();
   EndBlock(Last());
 
   Optimize();