Introduce CodeSourceMap object to hold pc -> token position mappings

runtime/vm/raw_object.cc

Index: runtime/vm/raw_object.cc
diff --git a/runtime/vm/raw_object.cc b/runtime/vm/raw_object.cc
index 730d50a04f0a37cac44440c18493bbaddaa339d1..d32b5abf8771f8d5bc1f9cb28092409c0f17534c 100644
--- a/runtime/vm/raw_object.cc
+++ b/runtime/vm/raw_object.cc
@@ -144,6 +144,13 @@ intptr_t RawObject::SizeFromClass() const {
       instance_size = PcDescriptors::InstanceSize(length);
       break;
     }
+    case kCodeSourceMapCid: {
+      const RawCodeSourceMap* raw_code_source_map =
+          reinterpret_cast<const RawCodeSourceMap*>(this);
+      intptr_t length = raw_code_source_map->ptr()->length_;
+      instance_size = CodeSourceMap::InstanceSize(length);
+      break;
+    }
     case kStackmapCid: {
       const RawStackmap* map = reinterpret_cast<const RawStackmap*>(this);
       intptr_t length = map->ptr()->length_;
@@ -589,6 +596,12 @@ intptr_t RawPcDescriptors::VisitPcDescriptorsPointers(
 }
 
 
+intptr_t RawCodeSourceMap::VisitCodeSourceMapPointers(
+    RawCodeSourceMap* raw_obj, ObjectPointerVisitor* visitor) {
+  return CodeSourceMap::InstanceSize(raw_obj->ptr()->length_);
+}
+
+
 intptr_t RawStackmap::VisitStackmapPointers(RawStackmap* raw_obj,
                                             ObjectPointerVisitor* visitor) {
   return Stackmap::InstanceSize(raw_obj->ptr()->length_);