Add experiment support to gentest

Summary:
This diff does two things
- Clean up some of the generated code making the files smaller.
- Add experiment support to generated tests allowing us to use gentest for things still being experimented with such as more compliant flex-basis behavior.

Reviewed By: gkassabli

Differential Revision: D4226734

fbshipit-source-id: 2cc1471c21883e8e326f16e7a8bb1a3657acd84b

gentest/gentest.js

@@ -46,36 +46,7 @@ function printTest(e, LTRContainer, RTLContainer, genericContainer) {
     ' * of patent rights can be found in the PATENTS file in the same directory.',
     ' */',
     '',
-    '/**',
-    ' * @Generated by gentest/gentest.sh with the following input',
-    ' *',
-  ]);
-
-  var indentation = 0;
-  e.push(genericContainer.innerHTML.split('\n').map(function(line) {
-    return line.trim();
-  }).filter(function(line) {
-    return line.length > 0 && line !== '<div id="default"></div>';
-  }).map(function(line) {
-    var result;
-    if (line.indexOf('</div') == 0) {
-      result = '  '.repeat(indentation - 1) + line;
-    } else {
-      result = '  '.repeat(indentation) + line;
-    }
-
-    indentation += (line.match(/<div/g) || []).length;
-    indentation -= (line.match(/<\/div/g) || []).length;
-    return result;
-  }).reduce(function(curr, prev) {
-    if (prev.indexOf('<div') == 0) {
-      prev = '\n' + prev;
-    }
-    return curr + '\n' + prev;
-  }));
-  e.push([
-    ' *',
-    ' */',
+    ' // @Generated by gentest/gentest.rb from gentest/fixtures/' + document.title + '.html',
     '',
   ]);
   e.emitPrologue();
@@ -86,7 +57,7 @@ function printTest(e, LTRContainer, RTLContainer, genericContainer) {
 
 
   for (var i = 0; i < genericLayoutTree.length; i++) {
-    e.emitTestPrologue(genericLayoutTree[i].name);
+    e.emitTestPrologue(genericLayoutTree[i].name, genericLayoutTree[i].experiments);
 
     if (genericLayoutTree[i].name == 'wrap_column') {
       // Modify width and left values due to both safari and chrome not abiding by the
@@ -127,7 +98,7 @@ function printTest(e, LTRContainer, RTLContainer, genericContainer) {
 
     assertTestTree(e, RTLLayoutTree[i], 'root', null);
 
-    e.emitTestEpilogue();
+    e.emitTestEpilogue(genericLayoutTree[i].experiments);
   }
   e.emitEpilogue();
 
@@ -443,6 +414,9 @@ function calculateTree(root) {
       style: getCSSLayoutStyle(child),
       declaredStyle: child.style,
       rawStyle: child.getAttribute('style'),
+      experiments: child.getAttribute('experiments')
+          ? child.getAttribute('experiments').split(' ')
+          : [],
     });
   }