fix(material/autocomplete): autocomplete panel gets cut off in mobile landscape

Updates fix to autocomplete panel which was getting cut off in mobile landscape
by correctly assigning const isHandsetLandscape to the subscription result.matches
value and thus if isHandsetLandscape is true then applying flexible dimensions,
grow after open and with viewport margin to the panel on open.

Fixes b/284148377

Author: essjay05

src/material/autocomplete/autocomplete-trigger.ts

@@ -900,18 +900,17 @@ export class MatAutocompleteTrigger
       this._handsetLandscapeBreakpointSubscription = this._breakpointObserver
         .observe(Breakpoints.HandsetLandscape)
         .subscribe(result => {
-          return result.matches;
+          // Check breakpoint if being viewed in HandsetLandscape via subscription (if not null)
+          const isHandsetLandscape = result.matches;
+          // Apply HandsetLandscape settings to prevent overlay cutoff in that breakpoint
+          // Fixes b/284148377
+          if (isHandsetLandscape) {
+            strategy.withFlexibleDimensions(true).withGrowAfterOpen(true).withViewportMargin(8);
+          }
+          return;
         });
     }
 
-    // Check breakpoint if being viewed in HandsetLandscape via subscription (if not null)
-    const isHandsetLandscape = this._handsetLandscapeBreakpointSubscription;
-    // Apply HandsetLandscape settings to prevent overlay cutoff in that breakpoint
-    // Fixes b/284148377
-    if (isHandsetLandscape) {
-      strategy.withFlexibleDimensions(true).withGrowAfterOpen(true).withViewportMargin(8);
-    }
-
     this._setStrategyPositions(strategy);
     this._positionStrategy = strategy;
     return strategy;