JSX: Respect original spacing and newlines better

Fixes #335.

Now this JSX:

```
/** @jsx React.DOM */
var HelloMessage = React.createClass({
  render: function() {
    return <div>
      Look!
      <a href=
        "http://www.facebook.com/">Facebook
      </a>
    </div>;
  }
});
```

produces

```
/** @jsx React.DOM */
var HelloMessage = React.createClass({displayName: 'HelloMessage',
  render: function() {
    return React.DOM.div(null,
      " Look! ",
      React.DOM.a( {href:
        "http://www.facebook.com/"}, "Facebook "
      )
    );
  }
});
```

rather than the less-desirable

```
/** @jsx React.DOM */
var HelloMessage = React.createClass({displayName: 'HelloMessage',
  render: function() {
    return React.DOM.div(null,
" Look! ",      React.DOM.a( {href:"http://www.facebook.com/"}, "Facebook "      ),
    );
  }
});
```

vendor/fbtransform/transforms/react.js

@@ -19,6 +19,7 @@
 var Syntax = require('esprima-fb').Syntax;
 
 var catchup = require('jstransform/src/utils').catchup;
+var catchupWhiteSpace = require('jstransform/src/utils').catchupWhiteSpace;
 var append = require('jstransform/src/utils').append;
 var move = require('jstransform/src/utils').move;
 var getDocblock = require('jstransform/src/utils').getDocblock;
@@ -110,19 +111,21 @@ function visitReactTag(traverse, object, path, state) {
       if (!isLast) {
         append(',', state);
       }
-    } else if (JSX_ATTRIBUTE_TRANSFORMS[attr.name.name]) {
-      move(attr.value.range[0], state);
-      append(JSX_ATTRIBUTE_TRANSFORMS[attr.name.name](attr), state);
-      move(attr.value.range[1], state);
-      if (!isLast) {
-        append(',', state);
-      }
-    } else if (attr.value.type === Syntax.Literal) {
-      move(attr.value.range[0], state);
-      renderXJSLiteral(attr.value, isLast, state);
     } else {
-      move(attr.value.range[0], state);
-      renderXJSExpressionContainer(traverse, attr.value, isLast, path, state);
+      move(attr.name.range[1], state);
+      // Use catchupWhiteSpace to skip over the '=' in the attribute
+      catchupWhiteSpace(attr.value.range[0], state);
+      if (JSX_ATTRIBUTE_TRANSFORMS[attr.name.name]) {
+        append(JSX_ATTRIBUTE_TRANSFORMS[attr.name.name](attr), state);
+        move(attr.value.range[1], state);
+        if (!isLast) {
+          append(',', state);
+        }
+      } else if (attr.value.type === Syntax.Literal) {
+        renderXJSLiteral(attr.value, isLast, state);
+      } else {
+        renderXJSExpressionContainer(traverse, attr.value, isLast, path, state);
+      }
     }
 
     if (isLast) {

vendor/fbtransform/transforms/xjs.js

@@ -172,6 +172,7 @@ function trimWithSingleSpace(string) {
 function renderXJSLiteral(object, isLast, state, start, end) {
   /** Added blank check filtering and triming*/
   var trimmedChildValue = safeTrim(object.value);
+  var hasFinalNewLine = false;
 
   if (trimmedChildValue) {
     // head whitespace
@@ -191,7 +192,7 @@ function renderXJSLiteral(object, isLast, state, start, end) {
     });
 
     var hasInitialNewLine = initialLines[0] !== lines[0];
-    var hasFinalNewLine =
+    hasFinalNewLine =
       initialLines[initialLines.length - 1] !== lines[lines.length - 1];
 
     var numLines = lines.length;
@@ -203,20 +204,18 @@ function renderXJSLiteral(object, isLast, state, start, end) {
       } else {
         var preString = '';
         var postString = '';
-        var leading = '';
+        var leading = line.match(/^[ \t]*/)[0];
 
         if (ii === 0) {
           if (hasInitialNewLine) {
             preString = ' ';
-            leading = '\n';
+            leading = '\n' + leading;
           }
           if (trimmedChildValueWithSpace.substring(0, 1) === ' ') {
             // If this is the first line, and the original content starts with
             // whitespace, place a single space at the beginning.
             preString = ' ';
           }
-        } else {
-          leading = line.match(/^[ \t]*/)[0];
         }
         if (!lastLine || trimmedChildValueWithSpace.substr(
              trimmedChildValueWithSpace.length - 1, 1) === ' ' ||
@@ -256,6 +255,9 @@ function renderXJSLiteral(object, isLast, state, start, end) {
   }
 
   // tail whitespace
+  if (hasFinalNewLine) {
+    append('\n', state);
+  }
   append(object.value.match(/[ \t]*$/)[0], state);
   move(object.range[1], state);
 }