use index instead of debugId

fixed chunk propagation

Author: sokra

lib/optimize/RemoveParentModulesPlugin.js

@@ -5,7 +5,7 @@
 function listToSet(list, chunk) {
 	var set = {};
 	list.forEach(function(module) {
-		set[module.debugId] = {
+		set[module._RemoveParentModulesPlugin_index] = {
 			module: module,
 			chunks: [chunk]
 		};
@@ -75,7 +75,10 @@ module.exports = RemoveParentModulesPlugin;
 RemoveParentModulesPlugin.prototype.apply = function(compiler) {
 	compiler.plugin("compilation", function(compilation) {
 		compilation.plugin(["optimize-chunks-basic", "optimize-extracted-chunks-basic"], function(chunks) {
-			var todo = chunks.slice().reverse();
+			this.modules.forEach(function(module, idx) {
+				module._RemoveParentModulesPlugin_index = idx;
+			})
+			var todo = chunks.slice();
 			todo.forEach(function(chunk, idx) {
 				chunk._RemoveParentModulesPlugin_processed = false;
 				chunk._RemoveParentModulesPlugin_availableModulesByChunk = {};
@@ -89,7 +92,7 @@ RemoveParentModulesPlugin.prototype.apply = function(compiler) {
 					chunk._RemoveParentModulesPlugin_processed = true;
 					continue;
 				}
-				var set = listToSet(chunk.modules);
+				var set = listToSet(chunk.modules, chunk);
 				if(availableModules)
 					set = mergeSets(set, availableModules);
 				chunk.chunks.forEach(function(child) {
@@ -110,10 +113,10 @@ RemoveParentModulesPlugin.prototype.apply = function(compiler) {
 				delete chunk._RemoveParentModulesPlugin_availableModules;
 				delete chunk._RemoveParentModulesPlugin_processed;
 				delete chunk._RemoveParentModulesPlugin_index;
+				if(chunk.entry) return;
 				if(!availableModules) return;
 				chunk.modules.slice().forEach(function(module) {
-					if(chunk.entry) return;
-					var info = availableModules[module.debugId];
+					var info = availableModules[module._RemoveParentModulesPlugin_index];
 					if(!info) return;
 					var parentChunksWithModule = info.chunks;
 					parentChunksWithModule = parentChunksWithModule.filter(function(chunk, idx) {