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/dex/mir_method_info.h b/compiler/dex/mir_method_info.h
index 3706012..946c74b 100644
--- a/compiler/dex/mir_method_info.h
+++ b/compiler/dex/mir_method_info.h
@@ -88,7 +88,7 @@
   // The type index of the class declaring the method, 0 if unresolved.
   uint16_t declaring_class_idx_;
   // The dex file that defines the class containing the method and the method,
-  // nullptr if unresolved.
+  // null if unresolved.
   const DexFile* declaring_dex_file_;
 };
 
@@ -223,7 +223,7 @@
   uintptr_t direct_code_;
   uintptr_t direct_method_;
   // Before Resolve(), target_dex_file_ and target_method_idx_ hold the verification-based
-  // devirtualized invoke target if available, nullptr and 0u otherwise.
+  // devirtualized invoke target if available, null and 0u otherwise.
   // After Resolve() they hold the actual target method that will be called; it will be either
   // a devirtualized target method or the compilation's unit's dex file and MethodIndex().
   const DexFile* target_dex_file_;