Make maps in monomorphic IC stubs weak.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index a5d0dbf4398fe0b53b5fa14c12f18522d96bf5da..35fae13d37af345b892f0ac7e347c27dc1f92eae 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -4547,7 +4547,9 @@ Handle<Map> NormalizedMapCache::Get(Handle<NormalizedMapCache> cache,
                     Map::kCodeCacheOffset) == 0);
       STATIC_ASSERT(Map::kDependentCodeOffset ==
                     Map::kCodeCacheOffset + kPointerSize);
-      int offset = Map::kDependentCodeOffset + kPointerSize;
+      STATIC_ASSERT(Map::kDependentICOffset ==
+                    Map::kDependentCodeOffset + kPointerSize);
+      int offset = Map::kDependentICOffset + kPointerSize;
       ASSERT(memcmp(fresh->address() + offset,
                     Handle<Map>::cast(result)->address() + offset,
                     Map::kSize - offset) == 0);
@@ -11535,6 +11537,13 @@ void Map::AddDependentCode(DependentCode::DependencyGroup group,
 }
 
 
+void Map::AddDependentIC(Handle<Code> stub) {
+  ASSERT(stub->next_code_link()->IsUndefined());
+  stub->set_next_code_link(dependent_ic());
+  set_dependent_ic(*stub);
+}
+
+
 DependentCode::GroupStartIndexes::GroupStartIndexes(DependentCode* entries) {
   Recompute(entries);
 }