Escape quotes when they appear as HTML entities in JSX text

Fixes microsoft#6241

Author: RyanCavanaugh

src/compiler/emitter.ts

@@ -7221,7 +7221,9 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
  // Replace entities like  
  result = result.replace(/&(\w+);/g, function(s: any, m: string) {
  if (entities[m] !== undefined) {
- return String.fromCharCode(entities[m]);
+ let ch = String.fromCharCode(entities[m]);
+ // " needs to be escaped
+ return ch === '"' ? '\\"' : ch;
  }
  else {
  return s;

tests/baselines/reference/tsxReactEmitEntities.js

@@ -8,7 +8,9 @@ declare module JSX {
 declare var React: any;
 
 <div>Dot goes here: &middot; &notAnEntity; </div>;
+<div>Be careful of &quot;-ed strings!</div>;
 
 
 //// [file.js]
 React.createElement("div", null, "Dot goes here: · &notAnEntity; ");
+React.createElement("div", null, "Be careful of \"-ed strings!");

tests/baselines/reference/tsxReactEmitEntities.symbols

@@ -19,3 +19,7 @@ declare var React: any;
 >div : Symbol(JSX.IntrinsicElements, Decl(file.tsx, 1, 22))
 >div : Symbol(JSX.IntrinsicElements, Decl(file.tsx, 1, 22))
 
+<div>Be careful of &quot;-ed strings!</div>;
+>div : Symbol(JSX.IntrinsicElements, Decl(file.tsx, 1, 22))
+>div : Symbol(JSX.IntrinsicElements, Decl(file.tsx, 1, 22))
+

tests/baselines/reference/tsxReactEmitEntities.types

@@ -20,3 +20,8 @@ declare var React: any;
 >div : any
 >div : any
 
+<div>Be careful of &quot;-ed strings!</div>;
+><div>Be careful of &quot;-ed strings!</div> : JSX.Element
+>div : any
+>div : any
+

tests/cases/conformance/jsx/tsxReactEmitEntities.tsx

@@ -9,3 +9,4 @@ declare module JSX {
 declare var React: any;
 
 <div>Dot goes here: &middot; &notAnEntity; </div>;
+<div>Be careful of &quot;-ed strings!</div>;