[turbofan] Fix several int vs size_t issues.

src/compiler/instruction-selector.cc

Index: src/compiler/instruction-selector.cc
diff --git a/src/compiler/instruction-selector.cc b/src/compiler/instruction-selector.cc
index d007fbf13d57fc00e8b20c6455bc981ad176633a..edb9943d34f3e3837592e62cb1f18aea9b377489 100644
--- a/src/compiler/instruction-selector.cc
+++ b/src/compiler/instruction-selector.cc
@@ -398,7 +398,7 @@ void InstructionSelector::InitializeCallBuffer(Node* call, CallBuffer* buffer,
                         buffer->descriptor->GetInputType(0)));
       break;
   }
-  DCHECK_EQ(1, static_cast<int>(buffer->instruction_args.size()));
+  DCHECK_EQ(1u, buffer->instruction_args.size());
 
   // If the call needs a frame state, we insert the state information as
   // follows (n is the number of value inputs to the frame state):