Attempt to unbreak build with MSVC 15.8.4

Bug: gn:51
Change-Id: I315ae11fcf0acc448757456cff10f6f97cd53791
Reviewed-on: https://gn-review.googlesource.com/c/4001
Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>

tools/gn/setup_unittest.cc

diff --git a/tools/gn/setup_unittest.cc b/tools/gn/setup_unittest.cc
index ab94ce1..20c8eff 100644
--- a/tools/gn/setup_unittest.cc
+++ b/tools/gn/setup_unittest.cc
@@ -14,7 +14,8 @@
 using SetupTest = TestWithScheduler;
 
 static void WriteFile(const base::FilePath& file, const std::string& data) {
-  CHECK(data.size() == base::WriteFile(file, data.data(), data.size()));
+  CHECK_EQ(static_cast<int>(data.size()),  // Way smaller than INT_MAX.
+           base::WriteFile(file, data.data(), data.size()));
 }
 
 TEST_F(SetupTest, DotGNFileIsGenDep) {