[dart2js] Pass box to inlined generative constructor body

There was a rare mismatch between arguments and parameters when
inlining a constructor body.

The full arguments at the call site of a constructor body (always in a
generative constructor factory) and the parameters at inlining would
not agree on needing a 'box' for the constructor's closed-over mutated
variables (parameters and locals) when the box was needed only for
locals closed over in an assertion.

The fix is to make the condition for accepting a box match the test
for generating the box in the caller.

Bug: 45943
Change-Id: I3b056cb710ffac72bec6943809e04472a838e5bf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/198741
Reviewed-by: Mayank Patke <fishythefish@google.com>
Commit-Queue: Stephen Adams <sra@google.com>

pkg/compiler/lib/src/ssa/builder_kernel.dart

@@ -6130,7 +6130,6 @@ class KernelSsaGraphBuilder extends ir.Visitor<void> with ir.VisitorVoidMixin {
     }
 
     ir.Member memberContextNode = _elementMap.getMemberContextNode(function);
-    bool hasBox = false;
     KernelToLocalsMap localsMap = _globalLocalsMap.getLocalsMap(function);
     forEachOrderedParameter(_elementMap, function,
         (ir.VariableDeclaration variable, {bool isElided}) {
@@ -6144,14 +6143,13 @@ class KernelSsaGraphBuilder extends ir.Visitor<void> with ir.VisitorVoidMixin {
           scopeData.isBoxedVariable(_localsMap, local)) {
         // The parameter will be a field in the box passed as the last
         // parameter. So no need to have it.
-        hasBox = true;
         return;
       }
       HInstruction argument = compiledArguments[argumentIndex++];
       localsHandler.updateLocal(local, argument);
     });
 
-    if (hasBox) {
+    if (forGenerativeConstructorBody && scopeData.requiresContextBox) {
       HInstruction box = compiledArguments[argumentIndex++];
       assert(box is HCreateBox);
       // TODO(sra): Make inlining of closures work. We should always call

tests/web/regress/45943_test.dart

@@ -12,7 +12,7 @@ class _InspectorOverlayLayer {
       return true;
     }());
     if (inDebugMode == false) {
-      throw Error();
+      print('Error');
     }
   }
 }

tests/web_2/regress/45943_test.dart

@@ -12,7 +12,7 @@ class _InspectorOverlayLayer {
       return true;
     }());
     if (inDebugMode == false) {
-      throw Error();
+      print('Error');
     }
   }
 }