Fix a few clang warnings (which -Werror treats as errors)

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index c0b8a4e01129e96545414606b84f0b3057dc8e49..f9f08a66417f8d9d416af7f685e52a65398feee8 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -4226,7 +4226,7 @@ template <typename T> static void USE(T) { }
 
 
 // This test is not intended to be run, just type checked.
-static void PersistentHandles() {
+static inline void PersistentHandles() {
   USE(PersistentHandles);
   Local<String> str = v8_str("foo");
   v8::Persistent<String> p_str = v8::Persistent<String>::New(str);
@@ -11793,14 +11793,21 @@ THREADED_TEST(PixelArray) {
   CHECK_EQ(28, result->Int32Value());
 
   i::Handle<i::Smi> value(i::Smi::FromInt(2));
-  i::SetElement(jsobj, 1, value, i::kNonStrictMode);
+  i::Handle<i::Object> no_failure;
+  no_failure = i::SetElement(jsobj, 1, value, i::kNonStrictMode);
+  ASSERT(!no_failure.is_null());
+  i::USE(no_failure);
   CHECK_EQ(2, i::Smi::cast(jsobj->GetElement(1)->ToObjectChecked())->value());
   *value.location() = i::Smi::FromInt(256);
-  i::SetElement(jsobj, 1, value, i::kNonStrictMode);
+  no_failure = i::SetElement(jsobj, 1, value, i::kNonStrictMode);
+  ASSERT(!no_failure.is_null());
+  i::USE(no_failure);
   CHECK_EQ(255,
            i::Smi::cast(jsobj->GetElement(1)->ToObjectChecked())->value());
   *value.location() = i::Smi::FromInt(-1);
-  i::SetElement(jsobj, 1, value, i::kNonStrictMode);
+  no_failure = i::SetElement(jsobj, 1, value, i::kNonStrictMode);
+  ASSERT(!no_failure.is_null());
+  i::USE(no_failure);
   CHECK_EQ(0, i::Smi::cast(jsobj->GetElement(1)->ToObjectChecked())->value());
 
   result = CompileRun("for (var i = 0; i < 8; i++) {"