Remove arrayClass from ClassObject. It seems to get only dozens of hits in
all of Zygote start-up.

There doesn't seem to be a measurable difference in the time printed in:
I/Zygote  ( 2247): ...preloaded 1147 classes in NNNNms.
diff --git a/vm/oo/Array.c b/vm/oo/Array.c
index 19a0f96..60da683 100644
--- a/vm/oo/Array.c
+++ b/vm/oo/Array.c
@@ -104,21 +104,13 @@
 
     assert(elemClassObj != NULL);
 
-    if (elemClassObj->arrayClass != NULL) {
-        arrayClass = elemClassObj->arrayClass;
-        LOGVV("using cached '%s' class for '%s'\n",
-            arrayClass->descriptor, elemClassObj->descriptor);
-    } else {
-        /* Simply prepend "[" to the descriptor. */
-        int nameLen = strlen(elemClassObj->descriptor);
-        char className[nameLen + 2];
+    /* Simply prepend "[" to the descriptor. */
+    int nameLen = strlen(elemClassObj->descriptor);
+    char className[nameLen + 2];
 
-        className[0] = '[';
-        memcpy(className+1, elemClassObj->descriptor, nameLen+1);
-        arrayClass = dvmFindArrayClass(className, elemClassObj->classLoader);
-        if (arrayClass != NULL)
-            elemClassObj->arrayClass = arrayClass;
-    }
+    className[0] = '[';
+    memcpy(className+1, elemClassObj->descriptor, nameLen+1);
+    arrayClass = dvmFindArrayClass(className, elemClassObj->classLoader);
 
     return arrayClass;
 }
@@ -708,4 +700,3 @@
         dvmMarkObject((Object *)gDvm.primitiveClass[i]);    // may be NULL
     }
 }
-