VM: Remove more duplicate code between AOT and JIT compiler.

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index ace33b03ee3ad5718a7b870aa6157c5f4f3abd56..4fee7933623f1f656c2cdf918910455eb3569739 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -806,7 +806,7 @@ bool CompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
 
         // Optimize (a << b) & c patterns, merge operations.
         // Run early in order to have more opportunity to optimize left shifts.
-        optimizer.TryOptimizePatterns();
+        flow_graph->TryOptimizePatterns();
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
 
         FlowGraphInliner::SetInliningId(flow_graph, 0);
@@ -953,7 +953,7 @@ bool CompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
         // Optimize (a << b) & c patterns, merge operations.
         // Run after CSE in order to have more opportunity to merge
         // instructions that have same inputs.
-        optimizer.TryOptimizePatterns();
+        flow_graph->TryOptimizePatterns();
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
 
         {