Add enough compiler support to compile empty functions on x64.

runtime/vm/code_generator_x64.cc

Index: runtime/vm/code_generator_x64.cc
diff --git a/runtime/vm/code_generator_x64.cc b/runtime/vm/code_generator_x64.cc
index 1c5ba7c4cd3ca7b31784fd7ab1e31f131c4f8f5d..892a24912bd57e7e716ecafdb7dfffb85880020f 100644
--- a/runtime/vm/code_generator_x64.cc
+++ b/runtime/vm/code_generator_x64.cc
@@ -62,75 +62,6 @@ CodeGeneratorState::~CodeGeneratorState() {
 }
 
 
-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) {
-    struct PcDesc data;
-    data.pc_offset = pc_offset;
-    data.kind = kind;
-    data.node_id = node_id;
-    data.token_index = token_index;
-    data.try_index = try_index;
-    list_.Add(data);
-  }
-
-  RawPcDescriptors* FinalizePcDescriptors(uword entry_point) {
-    intptr_t num_descriptors = Length();
-    const PcDescriptors& descriptors =
-        PcDescriptors::Handle(PcDescriptors::New(num_descriptors));
-    for (intptr_t i = 0; i < num_descriptors; i++) {
-      descriptors.AddDescriptor(i,
-                                (entry_point + PcOffset(i)),
-                                Kind(i),
-                                NodeId(i),
-                                TokenIndex(i),
-                                TryIndex(i));
-    }
-    return descriptors.raw();
-  }
-
- private:
-  GrowableArray<struct PcDesc> list_;
-  DISALLOW_COPY_AND_ASSIGN(DescriptorList);
-};
-
-
 class CodeGenerator::HandlerList : public ZoneAllocated {
  public:
   struct HandlerDesc {