fix(fxFlex): use correct type for basis validation in reflow case (#1095)

Fixes #1089

Author: CaerusKaru

src/lib/flex/flex/flex.ts

@@ -279,7 +279,7 @@ export class FlexDirective extends BaseDirective2 {
   protected triggerReflow() {
     const activatedValue = this.activatedValue;
     if (activatedValue !== undefined) {
-      const parts = validateBasis(activatedValue, this.flexGrow, this.flexShrink);
+      const parts = validateBasis(activatedValue + '', this.flexGrow, this.flexShrink);
       this.marshal.updateElement(this.nativeElement, this.DIRECTIVE_KEY, parts.join(' '));
     }
   }