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

src/ast/scopes.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ast/scopes.h"
 
 #include "src/accessors.h"
 #include "src/ast/scopeinfo.h"
 #include "src/bootstrapper.h"
 #include "src/messages.h"
@@ skipping 824 matching lines @@
     int end_pos = scope->end_position();
     DCHECK(beg_pos >= 0 && end_pos >= 0);
     if (beg_pos <= position && position < end_pos) {
       scope->GetNestedScopeChain(isolate, chain, position);
       return;
     }
   }
 }
 
 
+void Scope::CollectNonLocals(HashMap* non_locals) {
+  // Collect non-local variables referenced in the scope.
+  for (int i = 0; i < unresolved_.length(); i++) {

[rossberg, 2015/12/09 14:53:46]

This scares me! It assumes that all non-locals are still unresolved, which is
very (too) brittle. It may not even be the case for all variables (we may
resolve some more eagerly, I'm not sure, or may want to do so in the future).

+    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) {
   // Propagate the error to the topmost scope targeted by this scope analysis
   // phase.
   Scope* top = this;
   while (!top->is_script_scope() && !top->outer_scope()->already_resolved()) {
     top = top->outer_scope();
   }
 
@@ skipping 795 matching lines @@
       function_ != NULL && function_->proxy()->var()->IsContextSlot();
   return num_heap_slots() - Context::MIN_CONTEXT_SLOTS - num_global_slots() -
          (is_function_var_in_context ? 1 : 0);
 }
 
 
 int Scope::ContextGlobalCount() const { return num_global_slots(); }
 
 }  // namespace internal
 }  // namespace v8