Clean up some uses of Failures and MaybeObjects.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 68bd159f3791d498854bcd820847434bee53149d..0ad3fa74a7bfbd5dc60493cff9febf1835191347 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -661,11 +661,6 @@ bool MaybeObject::IsRetryAfterGC() {
 }
 
 
-bool MaybeObject::IsException() {
-  return this == Failure::Exception();
-}
-
-
 Failure* Failure::cast(MaybeObject* obj) {
   ASSERT(HAS_FAILURE_TAG(obj));
   return reinterpret_cast<Failure*>(obj);
@@ -1297,16 +1292,6 @@ AllocationSpace Failure::allocation_space() const {
 }
 
 
-Failure* Failure::InternalError() {
-  return Construct(INTERNAL_ERROR);
-}
-
-
-Failure* Failure::Exception() {
-  return Construct(EXCEPTION);
-}
-
-
 intptr_t Failure::value() const {
   return static_cast<intptr_t>(
       reinterpret_cast<uintptr_t>(this) >> kFailureTagSize);