Filter out synthetic variables from with scopes

src/ast/scopeinfo.cc

Index: src/ast/scopeinfo.cc
diff --git a/src/ast/scopeinfo.cc b/src/ast/scopeinfo.cc
index d3014274d40bf1abdf2cb708fdcde9f0be9bb273..8f4bdb625874f22e9ac98868242a11c6deac22df 100644
--- a/src/ast/scopeinfo.cc
+++ b/src/ast/scopeinfo.cc
@@ -618,6 +618,14 @@ bool ScopeInfo::VariableIsSynthetic(String* name) {
          name->Equals(name->GetHeap()->this_string());
 }
 
+bool Scope::VariableIsSynthetic(const AstRawString* name) {

[adamk, 2016/09/19 20:01:25]

Yikes, I think this should be in scopes.cc. If you want to have them in the same
file, they should be in the same class, in which case I think putting them both
in Scope makes sense (as public static methods).

+  // There's currently no flag stored on the ScopeInfo to indicate that a
+  // variable is a compiler-introduced temporary. However, to avoid conflict
+  // with user declarations, the current temporaries like .generator_object and
+  // .result start with a dot, so we can use that as a flag. It's a hack!
+  return name->length() == 0 || name->FirstCharacter() == '.' ||
+         name->IsOneByteEqualTo("this");
+}
 
 int ScopeInfo::StackSlotIndex(String* name) {
   DCHECK(name->IsInternalizedString());