Move CodeGenerator::DescriptorList into shared part.

runtime/vm/code_generator.h

Index: runtime/vm/code_generator.h
===================================================================
--- runtime/vm/code_generator.h	(revision 4579)
+++ runtime/vm/code_generator.h	(working copy)
@@ -122,6 +122,54 @@
   const Class& class_;
 };
 
+
+class CodeGenerator::DescriptorList : public ZoneAllocated {
+ public:
+  struct PcDesc {
+    intptr_t pc_offset;        // PC offset value of the descriptor.
+    PcDescriptors::Kind kind;  // Descriptor kind (kDeopt, kOther).
+    intptr_t node_id;          // AST node id.
+    intptr_t token_index;      // Token position in source of PC.
+    intptr_t try_index;        // Try block index of PC.
+  };
+
+  DescriptorList() : list_() {
+  }
+  ~DescriptorList() { }
+
+  intptr_t Length() const {
+    return list_.length();
+  }
+
+  intptr_t PcOffset(int index) const {
+    return list_[index].pc_offset;
+  }
+  PcDescriptors::Kind Kind(int index) const {
+    return list_[index].kind;
+  }
+  intptr_t NodeId(int index) const {
+    return list_[index].node_id;
+  }
+  intptr_t TokenIndex(int index) const {
+    return list_[index].token_index;
+  }
+  intptr_t TryIndex(int index) const {
+    return list_[index].try_index;
+  }
+
+  void AddDescriptor(PcDescriptors::Kind kind,
+                     intptr_t pc_offset,
+                     intptr_t node_id,
+                     intptr_t token_index,
+                     intptr_t try_index);
+
+  RawPcDescriptors* FinalizePcDescriptors(uword entry_point);
+
+ private:
+  GrowableArray<struct PcDesc> list_;
+  DISALLOW_COPY_AND_ASSIGN(DescriptorList);
+};
+
 }  // namespace dart
 
 #endif  // VM_CODE_GENERATOR_H_