[turbofan] IA: support better left operand for commutative binops

src/compiler/instruction-selector.h

Index: src/compiler/instruction-selector.h
diff --git a/src/compiler/instruction-selector.h b/src/compiler/instruction-selector.h
index a86e1560c6994c201094ecae149cd4ec1fca5c08..264f737ba7cb1207d519309801adc57b4476807b 100644
--- a/src/compiler/instruction-selector.h
+++ b/src/compiler/instruction-selector.h
@@ -84,6 +84,9 @@ class InstructionSelector FINAL {
     return Features(CpuFeatures::SupportedFeatures());
   }
 
+  // Checks if {node} is currently live.
+  bool IsLive(Node* node) const { return !IsDefined(node) && IsUsed(node); }
+
  private:
   friend class OperandGenerator;