Fixed history graph tooltip so dates are readable (#2872)

src/components/entity/ha-chart-base.js

@@ -60,6 +60,9 @@ class HaChartBase extends mixinBehaviors(
           width: 200px;
           transition: opacity 0.15s ease-in-out;
         }
+        :host([rtl]) .chartTooltip {
+          direction: rtl;
+        }
         .chartLegend ul,
         .chartTooltip ul {
           display: inline-block;
@@ -99,6 +102,10 @@ class HaChartBase extends mixinBehaviors(
           margin-right: 4px;
           width: 10px;
         }
+        :host([rtl]) .chartTooltip em {
+          margin-right: inherit;
+          margin-left: 4px;
+        }
         paper-icon-button {
           color: var(--secondary-text-color);
         }
@@ -169,6 +176,10 @@ class HaChartBase extends mixinBehaviors(
         }),
       },
       unit: Object,
+      rtl: {
+        type: Boolean,
+        reflectToAttribute: true,
+      },
     };
   }