Revert of [turbofan] Run everything after representation selection concurrently.

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index 304b1b8a5a980078030af27a164d613f70e5a4d9..9197e39eee383b5e345391af641f20b7b89a4d3e 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -1000,7 +1000,10 @@
     return RpoNumber::FromInt(static_cast<int>(value_));
   }
 
-  Handle<HeapObject> ToHeapObject() const;
+  Handle<HeapObject> ToHeapObject() const {
+    DCHECK_EQ(kHeapObject, type());
+    return bit_cast<Handle<HeapObject> >(static_cast<intptr_t>(value_));
+  }
 
  private:
   Type type_;