Fix bug in SkWriter32.

src/core/SkWriter32.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkWriter32.h"
 
 SkWriter32::SkWriter32(size_t minSize, void* storage, size_t storageSize) {
@@ skipping 43 matching lines @@
     SkASSERT(SkAlign4(size) == size);
 
     Block* block = fTail;
     SkASSERT(NULL == block || block->available() < size);
 
     if (NULL == block) {
         SkASSERT(NULL == fHead);
         fHead = fTail = block = Block::Create(SkMax32(size, fMinSize));
         SkASSERT(0 == fWrittenBeforeLastBlock);
     } else {
-        SkASSERT(fSize > 0);
         fWrittenBeforeLastBlock = fSize;
 
         fTail = Block::Create(SkMax32(size, fMinSize));
         block->fNext = fTail;
         block = fTail;
     }
     return block;
 }
 
 uint32_t* SkWriter32::peek32(size_t offset) {
@@ skipping 215 matching lines @@
 
 size_t SkWriter32::WriteStringSize(const char* str, size_t len) {
     if ((long)len < 0) {
         SkASSERT(str);
         len = strlen(str);
     }
     const size_t lenBytes = 4;    // we use 4 bytes to record the length
     // add 1 since we also write a terminating 0
     return SkAlign4(lenBytes + len + 1);
 }