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