fixed precedence of sequence expression in computed property name (#415)

Co-authored-by: sanex3339 <yarabotayuvyandex3339>

escodegen.js

@@ -983,7 +983,7 @@
             result.push('[');
         }
 
-        result.push(this.generateExpression(expr, Precedence.Sequence, E_TTT));
+        result.push(this.generateExpression(expr, Precedence.Assignment, E_TTT));
 
         if (computed) {
             result.push(']');

test/compare-acorn-es6/class-declaration.expected.js

@@ -0,0 +1,12 @@
+class ComputedKey {
+    [n1 + n2]() {
+    }
+}
+class AssignmentExpressionAsKey {
+    [n1 = n2]() {
+    }
+}
+class SequenceExpressionAsKey {
+    [(n1, n2)]() {
+    }
+}

test/compare-acorn-es6/class-declaration.expected.min.js

@@ -0,0 +1 @@
+class ComputedKey{[n1+n2](){}}class AssignmentExpressionAsKey{[n1=n2](){}}class SequenceExpressionAsKey{[(n1,n2)](){}}

test/compare-acorn-es6/class-declaration.js

@@ -0,0 +1,9 @@
+class ComputedKey {
+    [n1 + n2]() {}
+}
+class AssignmentExpressionAsKey {
+    [n1 = n2]() {}
+}
+class SequenceExpressionAsKey {
+    [(n1, n2)]() {}
+}