tools/gn: Remove code for forward_dependent_configs_from variable.

tools/gn/target_generator.cc

Index: tools/gn/target_generator.cc
diff --git a/tools/gn/target_generator.cc b/tools/gn/target_generator.cc
index 833b382e274147275463fa4b3cbc2577359c6ec8..366210c6de4e48f85576af5a9e2e87e5de96a4fb 100644
--- a/tools/gn/target_generator.cc
+++ b/tools/gn/target_generator.cc
@@ -247,10 +247,6 @@ bool TargetGenerator::FillDependencies() {
       return false;
   }
 
-  // This is a list of dependent targets to have their configs fowarded, so
-  // it goes here rather than in FillConfigs.
-  if (!FillForwardDependentConfigs())
-    return false;
   return true;
 }
 
@@ -359,14 +355,3 @@ bool TargetGenerator::FillGenericDeps(const char* var_name,
   }
   return !err_->has_error();
 }
-
-bool TargetGenerator::FillForwardDependentConfigs() {
-  const Value* value = scope_->GetValue(
-      variables::kForwardDependentConfigsFrom, true);
-  if (value) {
-    ExtractListOfUniqueLabels(*value, scope_->GetSourceDir(),
-                              ToolchainLabelForScope(scope_),
-                              &target_->forward_dependent_configs(), err_);
-  }
-  return !err_->has_error();
-}