[observatory] Add a 'GC' button to heap map.

runtime/observatory/lib/src/repositories/allocation_profile.dart

Index: runtime/observatory/lib/src/repositories/allocation_profile.dart
diff --git a/runtime/observatory/lib/src/repositories/allocation_profile.dart b/runtime/observatory/lib/src/repositories/allocation_profile.dart
index aedfb3a538fa98927fe14fdaceb7798324ac78c9..77a2caa0fdba93fd8748cf34838fc6647cc1acba 100644
--- a/runtime/observatory/lib/src/repositories/allocation_profile.dart
+++ b/runtime/observatory/lib/src/repositories/allocation_profile.dart
@@ -14,10 +14,10 @@ class AllocationProfileRepository implements M.AllocationProfileRepository {
     S.Isolate isolate = i as S.Isolate;
     assert(isolate != null);
     var params = {};
-    if (gc == true) {
+    if (gc) {
       params['gc'] = 'full';
     }
-    if (reset == true) {
+    if (reset) {
       params['reset'] = true;
     }
     final response = await isolate.invokeRpc(_api, params);