fix nested hoist_props substitution

fixes #2519

lib/compress.js

@@ -2815,7 +2815,7 @@ merge(Compressor.prototype, {
         if (!compressor.option("hoist_props") || compressor.has_directive("use asm")) return self;
         var top_retain = self instanceof AST_Toplevel && compressor.top_retain || return_false;
         var defs_by_id = Object.create(null);
-        return self.transform(new TreeTransformer(function(node) {
+        return self.transform(new TreeTransformer(function(node, descend) {
             if (node instanceof AST_VarDef) {
                 var sym = node.name, def, value;
                 if (sym.scope === self
@@ -2825,6 +2825,7 @@ merge(Compressor.prototype, {
                     && !top_retain(def)
                     && (value = sym.fixed_value()) === node.value
                     && value instanceof AST_Object) {
+                    descend(node, this);
                     var defs = new Dictionary();
                     var assignments = [];
                     value.properties.forEach(function(prop) {

test/compress/hoist_props.js

@@ -633,3 +633,34 @@ issue_2508_5: {
     }
     expect_stdout: true
 }
+
+issue_2519: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        hoist_props: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function testFunc() {
+            var dimensions = {
+                minX: 5,
+                maxX: 6,
+            };
+            var scale = 1;
+            var d = {
+                x: (dimensions.maxX + dimensions.minX) / 2,
+            };
+            return d.x * scale;
+        }
+        console.log(testFunc());
+    }
+    expect: {
+        function testFunc() {
+            return 1 * ((6 + 5) / 2);
+        }
+        console.log(testFunc());
+    }
+    expect_stdout: "5.5"
+}