diff -r bbb498ccb4ac -r 26e3035cdffc src/Types.h
--- a/src/Types.h	Sat Dec 22 23:18:57 2012 -0800
+++ b/src/Types.h	Mon Dec 24 02:49:20 2012 -0800
@@ -57,6 +57,9 @@
     // on 64-bit systems), and does not exist in language semantics.
     PrimitiveType_Native,
 
+    // Internal string object.
+    PrimitiveType_String,
+
     PrimitiveTypes_Total
 };
 
@@ -144,7 +147,7 @@
         return primitive_;
     }
     bool isPod() {
-        return isPrimitive() || isEnum() || isUnchecked();
+        return (isPrimitive() && !isString()) || isEnum() || isUnchecked();
     }
     PrimitiveType pod() {
         assert(isPod());
@@ -169,11 +172,18 @@
     bool isBool() {
         return isPrimitive() && primitive() == PrimitiveType_Bool;
     }
+    bool isString() {
+        return isPrimitive() && primitive() == PrimitiveType_String;
+    }
     bool isExternalArray() {
         return kind() == EXTERNAL_ARRAY;
     }
     bool isTraceable() {
-        return !isPrimitive();
+        return (isPrimitive() && primitive() == PrimitiveType_String) ||
+               isReference() ||
+               isArray() ||
+               isStruct() ||
+               isFunction();
     }
     bool isConst() {
         assert(isPrimitive() ||
@@ -250,7 +260,6 @@
     static ArrayType *NewExternal(Zone *zone, Handle<Type> contained);
 
     Type *innermost() {
-        assert(isArray());
         Type *temp = contained();
         while (temp->isArray())
             temp = ArrayType::cast(temp)->contained();
@@ -261,7 +270,6 @@
         return contained_;
     }
     bool isFixedLength() {
-        assert(isArray());
         return elements_ > 0;
     }
     bool isCharArray() {
@@ -273,12 +281,9 @@
         return elements_;
     }
     unsigned levels() {
-        assert(isArray());
         return levels_;
     }
     bool hasInlineElements() {
-        assert(isArray());
-
         // We don't allocate traceable elements inline, since there's no
         // point to the optimization; we're going to be allocating lots of
         // objects anyway (in theory).