Make line-starts 32-bits TypedData instead of Array of smis.

runtime/vm/kernel_binary_flowgraph.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/kernel_binary_flowgraph.h"
 
 #include "vm/compiler.h"
 #include "vm/longjump.h"
 #include "vm/object_store.h"
 
@@ skipping 7166 matching lines @@
     SkipBytes(length);
     intptr_t line_count = ReadUInt();
     for (intptr_t j = 0; j < line_count; ++j) {
       ReadUInt();
     }
   }
 
   return String::Handle(String::null());
 }
 
-Array& StreamingFlowGraphBuilder::GetLineStartsFor(intptr_t index) {
+TypedData& StreamingFlowGraphBuilder::GetLineStartsFor(intptr_t index) {
   AlternativeReadingScope alt(reader_);
   SetOffset(reader_->size() - 4);
   intptr_t library_count = reader_->ReadUInt32();
   SetOffset(reader_->size() - 4 - 4 * library_count - 3 * 4);
   SetOffset(reader_->ReadUInt32());  // read source table offset.
   intptr_t size = ReadUInt();        // read source table size.
   intptr_t uris_size = 0;
   for (intptr_t i = 0; i < size; ++i) {
     uris_size = ReadUInt();
   }
   SkipBytes(uris_size);
 
   // Read the source code strings and line starts.
   for (intptr_t i = 0; i < size; ++i) {
     intptr_t length = ReadUInt();
     SkipBytes(length);
     intptr_t line_count = ReadUInt();
     if (i == index) {
-      Array& array_object =
-          Array::Handle(Z, Array::New(line_count, Heap::kOld));
-      Smi& value = Smi::Handle(Z);
+      TypedData& line_starts = TypedData::Handle(
+          Z, TypedData::New(kTypedDataUint32ArrayCid, line_count, Heap::kOld));
       intptr_t previous_line_start = 0;
       for (intptr_t j = 0; j < line_count; ++j) {
         intptr_t line_start = ReadUInt() + previous_line_start;
-        value = Smi::New(line_start);
-        array_object.SetAt(j, value);
+        line_starts.SetUint32(j << 2, line_start);
         previous_line_start = line_start;
       }
-      return array_object;
+      return line_starts;
     } else {
       for (intptr_t j = 0; j < line_count; ++j) {
         ReadUInt();
       }
     }
   }
 
-  return Array::Handle(Array::null());
+  return TypedData::Handle(TypedData::null());
 }
 
 }  // namespace kernel
 }  // namespace dart
 
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)