Assert SkTDArray::pop() doesn't underflow.

include/core/SkTDArray.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkTDArray_DEFINED
@@ skipping 264 matching lines @@
         int count = SkMin32(max, fCount - index);
         memcpy(dst, fArray + index, sizeof(T) * count);
         return count;
     }
 
     void copy(T* dst) const {
         this->copyRange(dst, 0, fCount);
     }
 
     // routines to treat the array like a stack
-    T*          push() { return this->append(); }
-    void        push(const T& elem) { *this->append() = elem; }
-    const T&    top() const { return (*this)[fCount - 1]; }
-    T&          top() { return (*this)[fCount - 1]; }
-    void        pop(T* elem) { if (elem) *elem = (*this)[fCount - 1]; --fCount; }
-    void        pop() { --fCount; }
+    T*       push() { return this->append(); }
+    void     push(const T& elem) { *this->append() = elem; }
+    const T& top() const { return (*this)[fCount - 1]; }
+    T&       top() { return (*this)[fCount - 1]; }
+    void     pop(T* elem) { SkASSERT(fCount > 0); if (elem) *elem = (*this)[fCount - 1]; --fCount; }
+    void     pop() { SkASSERT(fCount > 0); --fCount; }
 
     void deleteAll() {
         T*  iter = fArray;
         T*  stop = fArray + fCount;
         while (iter < stop) {
             SkDELETE (*iter);
             iter += 1;
         }
         this->reset();
     }
@@ skipping 79 matching lines @@
         fReserve = count + 4;
         fReserve += fReserve / 4;
         fArray = (T*)sk_realloc_throw(fArray, fReserve * sizeof(T));
 #ifdef SK_DEBUG
         fData = (ArrayT*)fArray;
 #endif
     }
 };
 
 #endif