[ignition] Fix more -Wsign-compare warnings.

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

Index: test/unittests/interpreter/constant-array-builder-unittest.cc
diff --git a/test/unittests/interpreter/constant-array-builder-unittest.cc b/test/unittests/interpreter/constant-array-builder-unittest.cc
index 17a7bb060aa1422de602e2406b1c4f28d1494af2..ee010cfd6347e48b02e6a70bcc63587645b7dc11 100644
--- a/test/unittests/interpreter/constant-array-builder-unittest.cc
+++ b/test/unittests/interpreter/constant-array-builder-unittest.cc
@@ -50,7 +50,7 @@ TEST_F(ConstantArrayBuilderTest, ToFixedArray) {
     CHECK(builder.At(i)->SameValue(*object));
   }
   Handle<FixedArray> constant_array = builder.ToFixedArray(isolate());
-  CHECK_EQ(constant_array->length(), kNumberOfElements);
+  CHECK_EQ(constant_array->length(), static_cast<int>(kNumberOfElements));
   for (size_t i = 0; i < kNumberOfElements; i++) {
     CHECK(constant_array->get(static_cast<int>(i))->SameValue(*builder.At(i)));
   }
@@ -66,7 +66,7 @@ TEST_F(ConstantArrayBuilderTest, ToLargeFixedArray) {
     CHECK(builder.At(i)->SameValue(*object));
   }
   Handle<FixedArray> constant_array = builder.ToFixedArray(isolate());
-  CHECK_EQ(constant_array->length(), kNumberOfElements);
+  CHECK_EQ(constant_array->length(), static_cast<int>(kNumberOfElements));
   for (size_t i = 0; i < kNumberOfElements; i++) {
     CHECK(constant_array->get(static_cast<int>(i))->SameValue(*builder.At(i)));
   }
@@ -81,7 +81,7 @@ TEST_F(ConstantArrayBuilderTest, ToLargeFixedArrayWithReservations) {
                                 Smi::FromInt(static_cast<int>(i)));
   }
   Handle<FixedArray> constant_array = builder.ToFixedArray(isolate());
-  CHECK_EQ(constant_array->length(), kNumberOfElements);
+  CHECK_EQ(constant_array->length(), static_cast<int>(kNumberOfElements));
   for (size_t i = 0; i < kNumberOfElements; i++) {
     CHECK(constant_array->get(static_cast<int>(i))->SameValue(*builder.At(i)));
   }