Add parenthesis around binary expression inside of update expression (#1672)

This is not valid code but TypeScript parses it. It's easy to fix so might as well so we have one less failing test.

src/fast-path.js

@@ -295,6 +295,10 @@ FPp.needsParens = function() {
       }
 
     case "BinaryExpression": {
+      if (parent.type === "UpdateExpression") {
+        return true;
+      }
+
       const isLeftOfAForStatement = node => {
         let i = 0;
         while (node) {

tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap

@@ -214,6 +214,85 @@ interface i2 {
 
 `;
 
+exports[`decrementAndIncrementOperators.ts 1`] = `
+var x = 0;
+
+// errors
+1 ++;
+
+(1)++;
+(1)--;
+
+++(1);
+--(1);
+
+(1 + 2)++;
+(1 + 2)--;
+
+++(1 + 2);
+--(1 + 2);
+
+(x + x)++;
+(x + x)--;
+
+++(x + x);
+--(x + x);
+
+//OK
+x++;
+x--;
+
+++x;
+--x;
+
+(x)++;
+--(x);
+
+((x))++;
+((x))--;
+
+x[x++]++;
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+var x = 0;
+
+// errors
+1++;
+
+1++;
+1--;
+
+++1;
+--1;
+
+(1 + 2)++;
+(1 + 2)--;
+
+++(1 + 2);
+--(1 + 2);
+
+(x + x)++;
+(x + x)--;
+
+++(x + x);
+--(x + x);
+
+//OK
+x++;
+x--;
+
+++x;
+--x;
+
+x++;
+--x;
+
+x++;
+x--;
+
+x[x++]++;
+
+`;
+
 exports[`downlevelLetConst1.ts 1`] = `
 const~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 const;

tests/typescript/compiler/decrementAndIncrementOperators.ts

@@ -0,0 +1,37 @@
+var x = 0;
+
+// errors
+1 ++;
+
+(1)++;
+(1)--;
+
+++(1);
+--(1);
+
+(1 + 2)++;
+(1 + 2)--;
+
+++(1 + 2);
+--(1 + 2);
+
+(x + x)++;
+(x + x)--;
+
+++(x + x);
+--(x + x);
+
+//OK
+x++;
+x--;
+
+++x;
+--x;
+
+(x)++;
+--(x);
+
+((x))++;
+((x))--;
+
+x[x++]++;