Move some work from backend onClear to base class clear

src/gpu/GrReorderCommandBuilder.cpp

Index: src/gpu/GrReorderCommandBuilder.cpp
diff --git a/src/gpu/GrReorderCommandBuilder.cpp b/src/gpu/GrReorderCommandBuilder.cpp
index 4dc2201325852ef2f415d7958caea161356ce4f1..cf784b0c2de9217a58ddb046b361fd571da377a0 100644
--- a/src/gpu/GrReorderCommandBuilder.cpp
+++ b/src/gpu/GrReorderCommandBuilder.cpp
@@ -32,11 +32,10 @@ GrTargetCommands::Cmd* GrReorderCommandBuilder::recordDrawBatch(State* state, Gr
             if (Cmd::kDrawBatch_CmdType == reverseIter->type()) {
                 DrawBatch* previous = static_cast<DrawBatch*>(reverseIter.get());
 
-                // We cannot continue to search backwards if the render target changes
                 if (previous->fBatch->pipeline()->getRenderTarget() != rt) {
                     break;
                 }
-
+                // We cannot continue to search backwards if the render target changes
                 if (previous->fBatch->combineIfPossible(batch)) {
                     return NULL;
                 }
@@ -47,10 +46,11 @@ GrTargetCommands::Cmd* GrReorderCommandBuilder::recordDrawBatch(State* state, Gr
             } else if (Cmd::kClear_CmdType == reverseIter->type()) {
                 Clear* previous = static_cast<Clear*>(reverseIter.get());
 
+                if (previous->renderTarget() != rt) {
+                    break;
+                }
                 // We set the color to illegal if we are doing a discard.
-                // If we can ignore the rect, then we do a full clear
                 if (previous->fColor == GrColor_ILLEGAL ||
-                    previous->fCanIgnoreRect ||
                     intersect(batch->bounds(), previous->fRect)) {
                     break;
                 }