Remove didCharSizeChange logic from renderer

The only thing `didCharSizeChange` was used for was to figure out if we
need to refresh the character atlas or not. However, `acquireCharAtlas`
already inspects the atlas owned by this terminal, and if it matches, it
avoids generating a new atlas.

So if `didCharSizeChange` is true and it's not needed, it quickly bails
out as a no-op. But if `didCharSizeChange` is false, and it was needed
(possible given the complexity of testing all of these edge cases), it
could introduce a bug.

I think it makes sense to just get rid of `didCharSizeChange`, and just
always call `acquireCharAtlas`.

src/renderer/BaseRenderLayer.ts

@@ -93,7 +93,7 @@ export abstract class BaseRenderLayer implements IRenderLayer {
     }
   }
 
-  public resize(terminal: ITerminal, dim: IRenderDimensions, charSizeChanged: boolean): void {
+  public resize(terminal: ITerminal, dim: IRenderDimensions): void {
     this._scaledCellWidth = dim.scaledCellWidth;
     this._scaledCellHeight = dim.scaledCellHeight;
     this._scaledCharWidth = dim.scaledCharWidth;
@@ -110,9 +110,7 @@ export abstract class BaseRenderLayer implements IRenderLayer {
       this.clearAll();
     }
 
-    if (charSizeChanged) {
-      this._refreshCharAtlas(terminal, this._colors);
-    }
+    this._refreshCharAtlas(terminal, this._colors);
   }
 
   public abstract reset(terminal: ITerminal): void;