expose component v-model expression on passed data

Author: yyx990803

flow/compiler.js

@@ -121,6 +121,7 @@ declare type ASTElement = {
   model?: {
     value: string;
     callback: string;
+    expression: string;
   };
 
   directives?: Array<ASTDirective>;

src/compiler/codegen/index.js

@@ -220,7 +220,13 @@ function genData (el: ASTElement): string {
   }
   // component v-model
   if (el.model) {
-    data += `model:{value:${el.model.value},callback:${el.model.callback}},`
+    data += `model:{value:${
+      el.model.value
+    },callback:${
+      el.model.callback
+    },expression:${
+      el.model.expression
+    }},`
   }
   // inline-template
   if (el.inlineTemplate) {

src/compiler/directives/model.js

@@ -25,6 +25,7 @@ export function genComponentModel (
 
   el.model = {
     value: `(${value})`,
+    expression: `"${value}"`,
     callback: `function (${baseValueExpression}) {${assignment}}`
   }
 }