[debugger] fix debug-evaluate wrt shadowed context var.

src/ast/scopes.cc

Index: src/ast/scopes.cc
diff --git a/src/ast/scopes.cc b/src/ast/scopes.cc
index cf5dd29b66ed448d6c59891996749a08eed92eb2..42f7972742c1a8f0b5113759c6b1993c48595cda 100644
--- a/src/ast/scopes.cc
+++ b/src/ast/scopes.cc
@@ -842,6 +842,24 @@ void Scope::GetNestedScopeChain(Isolate* isolate,
 }
 
 
+void Scope::CollectNonLocals(HashMap* non_locals) {
+  // Collect non-local variables referenced in the scope.
+  // TODO(yangguo): store non-local variables explicitly if we can no longer
+  //                rely on unresolved_ to find them.
+  for (int i = 0; i < unresolved_.length(); i++) {
+    VariableProxy* proxy = unresolved_[i];
+    if (proxy->is_resolved() && proxy->var()->IsStackAllocated()) continue;
+    Handle<String> name = proxy->name();
+    void* key = reinterpret_cast<void*>(name.location());
+    HashMap::Entry* entry = non_locals->LookupOrInsert(key, name->Hash());
+    entry->value = key;
+  }
+  for (int i = 0; i < inner_scopes_.length(); i++) {
+    inner_scopes_[i]->CollectNonLocals(non_locals);
+  }
+}
+
+
 void Scope::ReportMessage(int start_position, int end_position,
                           MessageTemplate::Template message,
                           const AstRawString* arg) {