fix(directive): Title of first header is repeated for all columns if headers are being used on first column

In order to get the header to decorate a row, use preceding element on the same row, if it is a <th>

Fixes #10

Author: awerlang

src/directive.js

@@ -11,7 +11,8 @@ function wtResponsiveTable() {
                 Array.prototype.forEach.call(rows, function(row) {
                     var headerIndex = 0; 
                     Array.prototype.forEach.call(row.querySelectorAll('td'), function (value, index) {
-                        var title = headers.item(headerIndex).textContent;
+                        var th = value.parentElement.querySelector('th') || headers.item(headerIndex); 
+                        var title = th.textContent;
                         if (title && !value.getAttributeNode('data-title')) {
                             value.setAttribute('data-title', title);
                         }

tests/directive.spec.js

@@ -82,6 +82,44 @@ describe('directive', function () {
 		expect(headerRow.eq(3).attr('data-title')).toBeUndefined();
 	});
 
+	it('supports <th> as first column of each <tr>', function () {
+		var markup = [
+		    '<table wt-responsive-table>',
+	    '        <tr>',
+	    '            <th>First title</th>',
+	    '            <td>First column</td>',
+	    '        </tr>',
+	    '        <tr>',
+	    '            <th>Second title</th>',
+	    '            <td>Second column</td>',
+	    '        </tr>',
+	    '        <tr>',
+	    '            <th>Third title</th>',
+	    '            <td>Third column</td>',
+	    '        </tr>',
+	    '        <tr>',
+	    '            <th>Forth title</th>',
+	    '            <td>Forth column</td>',
+	    '        </tr>',
+		    '</table>'
+		].join('');
+		var element = angular.element(markup);
+		document.body.appendChild(element[0]);
+		$compile(element);
+
+		var firstDataRow = element.find('tr td');
+		expect(firstDataRow.eq(0).attr('data-title')).toBe('First title');
+		expect(firstDataRow.eq(1).attr('data-title')).toBe('Second title');
+		expect(firstDataRow.eq(2).attr('data-title')).toBe('Third title');
+		expect(firstDataRow.eq(3).attr('data-title')).toBe('Forth title');
+
+		var headerRow = element.find('tr th');
+		expect(headerRow.eq(0).attr('data-title')).toBeUndefined();
+		expect(headerRow.eq(1).attr('data-title')).toBeUndefined();
+		expect(headerRow.eq(2).attr('data-title')).toBeUndefined();
+		expect(headerRow.eq(3).attr('data-title')).toBeUndefined();
+	});
+
 	it('supports colspan', function () {
 		var markup = [
 		    '<table wt-responsive-table>',