Remove tooltip constructor fallbacks, this.chart and this._chart (#10612)

* remove tooltip fallbacks/backwards compatability in constructor

* increase size limit

Author: LeeLenaleee

.size-limit.cjs

@@ -41,7 +41,7 @@ module.exports = [
   },
   {
     path: 'dist/chart.js',
-    limit: '22 KB',
+    limit: '22.2 KB',
     import: '{ CategoryScale, LinearScale, LogarithmicScale, RadialLinearScale, TimeScale, TimeSeriesScale }',
     running: false,
     modifyWebpackConfig

docs/migration/v4-migration.md

@@ -31,3 +31,5 @@ A number of changes were made to the configuration options passed to the `Chart`
 
 ### General
 * Removed fallback to `fontColor` for the legend text and strikethrough color.
+* Removed `config._chart` fallback for `this.chart` in the filler plugin.
+* Removed `this._chart` in the filler plugin.

src/plugins/plugin.tooltip.js

@@ -465,9 +465,7 @@ export class Tooltip extends Element {
     this._tooltipItems = [];
     this.$animations = undefined;
     this.$context = undefined;
-    // TODO: V4, remove config._chart and this._chart backward compatibility aliases
-    this.chart = config.chart || config._chart;
-    this._chart = this.chart;
+    this.chart = config.chart;
     this.options = config.options;
     this.dataPoints = undefined;
     this.title = undefined;