Fix debugger's SaveAs functionality

src/utils/debugger/SkDebugCanvas.cpp

Index: src/utils/debugger/SkDebugCanvas.cpp
diff --git a/src/utils/debugger/SkDebugCanvas.cpp b/src/utils/debugger/SkDebugCanvas.cpp
index 684c5cd17b76bf072f110c07bc4f0dc4dd8c9f33..3b68365fc13a4c869180e409f8223fbc04ed41cc 100644
--- a/src/utils/debugger/SkDebugCanvas.cpp
+++ b/src/utils/debugger/SkDebugCanvas.cpp
@@ -61,6 +61,8 @@ void SkDebugCanvas::addDrawCommand(SkDrawCommand* command) {
 }
 
 void SkDebugCanvas::draw(SkCanvas* canvas) {
+    fDrawNeedsReset = true;
+
     if (!fCommandVector.isEmpty()) {
         this->drawTo(canvas, fCommandVector.count() - 1);
     }