make SkRBuffer always validate

BUG=skia:6102

Change-Id: Ic9fb259b2e980d00e179340945c50492f1803a4f
Reviewed-on: https://skia-review.googlesource.com/6736
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/src/core/SkRegion.cpp b/src/core/SkRegion.cpp
index b3b1831..1123cf0 100644
--- a/src/core/SkRegion.cpp
+++ b/src/core/SkRegion.cpp
@@ -1128,9 +1128,9 @@
 }
 
 size_t SkRegion::readFromMemory(const void* storage, size_t length) {
-    SkRBufferWithSizeCheck  buffer(storage, length);
-    SkRegion                tmp;
-    int32_t                 count;
+    SkRBuffer   buffer(storage, length);
+    SkRegion    tmp;
+    int32_t     count;
 
     if (buffer.readS32(&count) && (count >= 0) && buffer.read(&tmp.fBounds, sizeof(tmp.fBounds))) {
         if (count == 0) {