Minor clarifications and simplifications.

src/types.cc

Index: src/types.cc
diff --git a/src/types.cc b/src/types.cc
index db638ed141d604e95ffe7ab9f9099aac0ba34a2d..da86ef2398130ec2dad1195e05d53b6d5def2e8d 100644
--- a/src/types.cc
+++ b/src/types.cc
@@ -313,16 +313,12 @@ bool TypeImpl<Config>::SlowIs(TypeImpl* that) {
 
   // T <= (T1 \/ ... \/ Tn)  <=>  (T <= T1) \/ ... \/ (T <= Tn)
   // (iff T is not a union)
-  ASSERT(!this->IsUnion());
-  if (that->IsUnion()) {
-    UnionHandle unioned = handle(that->AsUnion());
-    for (int i = 0; i < unioned->Length(); ++i) {
-      if (this->Is(unioned->Get(i))) return true;
-      if (this->IsBitset()) break;  // Fast fail, only first field is a bitset.
-    }
-    return false;
+  ASSERT(!this->IsUnion() && that->IsUnion());
+  UnionHandle unioned = handle(that->AsUnion());
+  for (int i = 0; i < unioned->Length(); ++i) {
+    if (this->Is(unioned->Get(i))) return true;
+    if (this->IsBitset()) break;  // Fast fail, only first field is a bitset.
   }
-
   return false;
 }
 
@@ -382,11 +378,8 @@ bool TypeImpl<Config>::Maybe(TypeImpl* that) {
   }
 
   ASSERT(!this->IsUnion() && !that->IsUnion());
-  if (this->IsBitset()) {
-    return BitsetType::IsInhabited(this->AsBitset() & that->BitsetLub());
-  }
-  if (that->IsBitset()) {
-    return BitsetType::IsInhabited(this->BitsetLub() & that->AsBitset());
+  if (this->IsBitset() || that->IsBitset()) {
+    return BitsetType::IsInhabited(this->BitsetLub() & that->BitsetLub());
   }
   if (this->IsClass()) {
     return that->IsClass()