Make compound assignment operators (+= etc) fail validation.

Author: gasman

lib/validate.js

@@ -794,6 +794,7 @@ Vp.expression = function expression(e) {
 
         when({
             type: 'AssignmentExpression',
+            operator: '=',
             left: match.var('left', { type: match.some('Identifier', 'MemberExpression') }),
             right: match.var('right')
         }, function(vars) {

test/index.js

@@ -322,3 +322,11 @@ exports.testConditionalExpressionDifferentSubtypes = asmAssert.one(
         return (1 ? (2 < 3) : 4)|0;
     },
     { pass: true });
+
+exports.testCompoundAssignment = asmAssert.one(
+    "compound assignment operations such as += are disallowed",
+    function f() {
+        var x = 0;
+        x += 1;
+    },
+    { pass: false });