Introduce exception object and remove some uses of MaybeObject::IsFailure().

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index f1a0bfa52b133da27ea64e3facf02c319a297924..87651ee48330040b56c8c804135ffda00f0a2eac 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -2561,6 +2561,7 @@ bool Heap::CreateInitialMaps() {
     ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, uninitialized);
     ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, arguments_marker);
     ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, no_interceptor_result_sentinel);
+    ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, exception);
     ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, termination_exception);
 
     for (unsigned i = 0; i < ARRAY_SIZE(string_type_table); i++) {
@@ -2865,6 +2866,12 @@ bool Heap::CreateInitialObjects() {
                            handle(Smi::FromInt(-3), isolate()),
                            Oddball::kOther));
 
+  set_exception(
+      *factory->NewOddball(factory->exception_map(),
+                           "exception",
+                           handle(Smi::FromInt(-5), isolate()),
+                           Oddball::kException));
+
   for (unsigned i = 0; i < ARRAY_SIZE(constant_string_table); i++) {
     Handle<String> str =
         factory->InternalizeUtf8String(constant_string_table[i].contents);