Split HPhase for Lithium and Hydrogen using common CompilationPhase base.

src/lithium.cc

Index: src/lithium.cc
diff --git a/src/lithium.cc b/src/lithium.cc
index 2993c9aa73155bbfad9122a3d021d08f9107c761..b22fdf6e2883d9d6fc9a1da188d41fc4c02634b3 100644
--- a/src/lithium.cc
+++ b/src/lithium.cc
@@ -307,7 +307,7 @@ Label* LChunk::GetAssemblyLabel(int block_id) const {
 }
 
 void LChunk::MarkEmptyBlocks() {
-  HPhase phase("L_Mark empty blocks", this);
+  LPhase phase("L_Mark empty blocks", this);
   for (int i = 0; i < graph()->blocks()->length(); ++i) {
     HBasicBlock* block = graph()->blocks()->at(i);
     int first = block->first_instruction_index();
@@ -491,4 +491,11 @@ void LChunk::set_allocated_double_registers(BitVector* allocated_registers) {
 }
 
 
+LPhase::~LPhase() {
+  if (ShouldProduceTraceOutput()) {
+    isolate()->GetHTracer()->TraceLithium(name(), chunk_);
+  }
+}
+
+
 } }  // namespace v8::internal