Fix a sign-compare error to make gcc 4.9.2 happy.

This is from
https://chromium.googlesource.com/v8/v8/+/347fa90626a448e3535cf6aa100124dfd5b711ce

BUG=

Review URL: https://codereview.chromium.org/1365113003

Cr-Commit-Position: refs/heads/master@{#30932}

src/interpreter/bytecode-array-builder.cc

@@ -76,7 +76,8 @@ Handle<BytecodeArray> BytecodeArrayBuilder::ToBytecodeArray() {
 
 template <size_t N>
 void BytecodeArrayBuilder::Output(uint8_t(&bytes)[N]) {
-  DCHECK_EQ(Bytecodes::NumberOfOperands(Bytecodes::FromByte(bytes[0])), N - 1);
+  DCHECK_EQ(Bytecodes::NumberOfOperands(Bytecodes::FromByte(bytes[0])),
+            static_cast<int>(N) - 1);
   last_bytecode_start_ = bytecodes()->size();
   for (int i = 1; i < static_cast<int>(N); i++) {
     DCHECK(OperandIsValid(Bytecodes::FromByte(bytes[0]), i - 1, bytes[i]));