Initialize a variable in GrDrawTarget::drawPaths

Initialize the device bounds rect variable before use in GrDrawTarget::drawPaths.

R=rmistry@google.com, jvanverth@google.com, mtklein@google.com

Author: kkinnunen@nvidia.com

Review URL: https://codereview.chromium.org/355603003
diff --git a/src/gpu/GrDrawTarget.cpp b/src/gpu/GrDrawTarget.cpp
index 7cdb743..b90193f 100644
--- a/src/gpu/GrDrawTarget.cpp
+++ b/src/gpu/GrDrawTarget.cpp
@@ -560,7 +560,8 @@
     const GrDrawState* drawState = &getDrawState();
 
     SkRect devBounds;
-    for (int i = 0; i < pathCount; ++i) {
+    transforms[0].mapRect(&devBounds, paths[0]->getBounds());
+    for (int i = 1; i < pathCount; ++i) {
         SkRect mappedPathBounds;
         transforms[i].mapRect(&mappedPathBounds, paths[i]->getBounds());
         devBounds.join(mappedPathBounds);