Fixup html entity number

src/constants/string_mappings.js

@@ -10,27 +10,32 @@
 'use strict';
 
 // N.B. HTML entities are listed without the leading '&' and trailing ';'
+// https://www.freeformatter.com/html-entities.html
 
 module.exports = {
-
     entityToUnicode: {
         'mu': 'μ',
+        '#956': 'μ',
+
         'amp': '&',
+        '#28': '&',
+
         'lt': '<',
+        '#60': '<',
+
         'gt': '>',
+        '#62': '>',
+
         'nbsp': ' ',
+        '#160': ' ',
+
         'times': '×',
+        '#215': '×',
+
         'plusmn': '±',
-        'deg': '°'
-    },
-
-    unicodeToEntity: {
-        '&': 'amp',
-        '<': 'lt',
-        '>': 'gt',
-        '"': 'quot',
-        '\'': '#x27',
-        '\/': '#x2F'
-    }
+        '#177': '±',
 
+        'deg': '°',
+        '#176': '°'
+    }
 };

test/jasmine/tests/svg_text_utils_test.js

@@ -262,6 +262,15 @@ describe('svg+text utils', function() {
             expect(node.text()).toEqual('100μ & < 10 > 0  100 × 20 ± 0.5 °');
         });
 
+        it('decodes some HTML entities in text (number case)', function() {
+            var node = mockTextSVGElement(
+                '100&#956; &#28; &#60; 10 &#62; 0 &#160;' +
+                '100 &#215; 20 &#177; 0.5 &#176;'
+            );
+
+            expect(node.text()).toEqual('100μ & < 10 > 0  100 × 20 ± 0.5 °');
+        });
+
         it('supports superscript by itself', function() {
             var node = mockTextSVGElement('<sup>123</sup>');
             expect(node.html()).toBe(