[Interpreter] Adds an optimization to remove redundant Ldar/Star.

test/unittests/interpreter/bytecode-array-builder-unittest.cc

Index: test/unittests/interpreter/bytecode-array-builder-unittest.cc
diff --git a/test/unittests/interpreter/bytecode-array-builder-unittest.cc b/test/unittests/interpreter/bytecode-array-builder-unittest.cc
index 30202c9d7252c9b42c544b9778f4782ce430e8df..8972beececb16800b0c4705b58afb32cd689651a 100644
--- a/test/unittests/interpreter/bytecode-array-builder-unittest.cc
+++ b/test/unittests/interpreter/bytecode-array-builder-unittest.cc
@@ -39,9 +39,12 @@ TEST_F(BytecodeArrayBuilderTest, AllBytecodesGenerated) {
       .LoadTrue()
       .LoadFalse();
 
-  // Emit accumulator transfers.
+  // Emit accumulator transfers. Stores followed by loads to the same register
+  // are not generated. Hence, a dummy instruction in between.
   Register reg(0);
-  builder.LoadAccumulatorWithRegister(reg).StoreAccumulatorInRegister(reg);
+  builder.LoadAccumulatorWithRegister(reg)
+      .LoadNull()
+      .StoreAccumulatorInRegister(reg);
 
   // Emit global load / store operations.
   builder.LoadGlobal(0, 1, LanguageMode::SLOPPY, TypeofMode::NOT_INSIDE_TYPEOF)