simple fix for preabandon valgrind error

src/gpu/GrAtlasTextContext.cpp

Index: src/gpu/GrAtlasTextContext.cpp
diff --git a/src/gpu/GrAtlasTextContext.cpp b/src/gpu/GrAtlasTextContext.cpp
index ad56e89f8ba5bb41b8d1949f05ad929af3144553..56ad9d2d998430f97ab0d5ab9cb6f2dc733cb595 100644
--- a/src/gpu/GrAtlasTextContext.cpp
+++ b/src/gpu/GrAtlasTextContext.cpp
@@ -360,6 +360,11 @@ void GrAtlasTextContext::drawTextBlob(GrRenderTarget* rt, const GrClip& clip,
                                       const SkPaint& skPaint, const SkMatrix& viewMatrix,
                                       const SkTextBlob* blob, SkScalar x, SkScalar y,
                                       SkDrawFilter* drawFilter, const SkIRect& clipBounds) {
+    // If we have been abandoned, then don't draw
+    if (!fContext->getTextTarget()) {
+        return;
+    }
+
     SkAutoTUnref<BitmapTextBlob> cacheBlob;
     SkMaskFilter::BlurRec blurRec;
     BitmapTextBlob::Key key;