Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/compiler/common_compiler_test.cc b/compiler/common_compiler_test.cc
index 05cb8b4..5a9e04f 100644
--- a/compiler/common_compiler_test.cc
+++ b/compiler/common_compiler_test.cc
@@ -263,7 +263,7 @@
   mirror::Class* klass = class_linker_->FindClass(self, class_descriptor.c_str(), class_loader);
   CHECK(klass != nullptr) << "Class not found " << class_name;
   mirror::ArtMethod* method = klass->FindVirtualMethod(method_name, signature);
-  CHECK(method != NULL) << "Virtual method not found: "
+  CHECK(method != nullptr) << "Virtual method not found: "
       << class_name << "." << method_name << signature;
   CompileMethod(method);
 }