Reland of "Store SharedFunctionInfos of a Script in a FixedArray indexed by their ID"

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index de9c44079519143b595054d83721e2c61ffb63b3..a75ece1bf312ddc292a7cd66b267542a3116b0be 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -1244,7 +1244,7 @@ bool Debug::PrepareFunctionForBreakPoints(Handle<SharedFunctionInfo> shared) {
   // cover this, because the given function might have been inlined into code
   // for which no JSFunction exists.
   {
-    SharedFunctionInfo::Iterator iterator(isolate_);
+    SharedFunctionInfo::GlobalIterator iterator(isolate_);
     while (SharedFunctionInfo* shared = iterator.Next()) {
       shared->ClearCodeFromOptimizedCodeMap();
     }
@@ -1335,24 +1335,18 @@ void FindBreakablePositions(Handle<DebugInfo> debug_info, int start_position,
 bool Debug::GetPossibleBreakpoints(Handle<Script> script, int start_position,
                                    int end_position, std::set<int>* positions) {
   while (true) {
-    if (!script->shared_function_infos()->IsWeakFixedArray()) return false;
-
-    WeakFixedArray* infos =
-        WeakFixedArray::cast(script->shared_function_infos());
     HandleScope scope(isolate_);
     List<Handle<SharedFunctionInfo>> candidates;
-    {
-      WeakFixedArray::Iterator iterator(infos);
-      SharedFunctionInfo* info;
-      while ((info = iterator.Next<SharedFunctionInfo>())) {
-        if (info->end_position() < start_position ||
-            info->start_position() >= end_position) {
-          continue;
-        }
-        if (!info->IsSubjectToDebugging()) continue;
-        if (!info->HasDebugCode() && !info->allows_lazy_compilation()) continue;
-        candidates.Add(i::handle(info));
+    SharedFunctionInfo::ScriptIterator iterator(script);
+    for (SharedFunctionInfo* info = iterator.Next(); info != nullptr;
+         info = iterator.Next()) {
+      if (info->end_position() < start_position ||
+          info->start_position() >= end_position) {
+        continue;
       }
+      if (!info->IsSubjectToDebugging()) continue;
+      if (!info->HasDebugCode() && !info->allows_lazy_compilation()) continue;
+      candidates.Add(i::handle(info));
     }
 
     bool was_compiled = false;
@@ -1462,15 +1456,14 @@ Handle<Object> Debug::FindSharedFunctionInfoInScript(Handle<Script> script,
     // find the inner most function containing this position.
     // If there is no shared function info for this script at all, there is
     // no point in looking for it by walking the heap.
-    if (!script->shared_function_infos()->IsWeakFixedArray()) break;
 
     SharedFunctionInfo* shared;
     {
       SharedFunctionInfoFinder finder(position);
-      WeakFixedArray::Iterator iterator(script->shared_function_infos());
-      SharedFunctionInfo* candidate;
-      while ((candidate = iterator.Next<SharedFunctionInfo>())) {
-        finder.NewCandidate(candidate);
+      SharedFunctionInfo::ScriptIterator iterator(script);
+      for (SharedFunctionInfo* info = iterator.Next(); info != nullptr;
+           info = iterator.Next()) {
+        finder.NewCandidate(info);
       }
       shared = finder.Result();
       if (shared == NULL) break;