Remove errors/warnings from tautological comparisons.

Change-Id: I2728b08d55abccd14c111c6c9da93068d4e14275
diff --git a/runtime/gc/heap.cc b/runtime/gc/heap.cc
index e9adca0..1e053eb 100644
--- a/runtime/gc/heap.cc
+++ b/runtime/gc/heap.cc
@@ -680,15 +680,11 @@
 }
 
 void Heap::RegisterGCAllocation(size_t bytes) {
-  if (this != nullptr) {
-    gc_memory_overhead_.FetchAndAddSequentiallyConsistent(bytes);
-  }
+  gc_memory_overhead_.FetchAndAddSequentiallyConsistent(bytes);
 }
 
 void Heap::RegisterGCDeAllocation(size_t bytes) {
-  if (this != nullptr) {
-    gc_memory_overhead_.FetchAndSubSequentiallyConsistent(bytes);
-  }
+  gc_memory_overhead_.FetchAndSubSequentiallyConsistent(bytes);
 }
 
 void Heap::DumpGcPerformanceInfo(std::ostream& os) {
@@ -1057,9 +1053,6 @@
 }
 
 void Heap::VerifyObjectBody(mirror::Object* obj) {
-  if (this == nullptr && verify_object_mode_ == kVerifyObjectModeDisabled) {
-    return;
-  }
   // Ignore early dawn of the universe verifications.
   if (UNLIKELY(static_cast<size_t>(num_bytes_allocated_.LoadRelaxed()) < 10 * KB)) {
     return;