Populate previous_def/super with captured block args

The previous_def and super keywords do not propagate blocks.
See: https://github.com/crystal-lang/crystal/issues/10399
This works around the issue by populating arguments if the method uses a block.

spec/issues/github_issue_48_spec.cr

@@ -29,6 +29,15 @@ Spectator.describe "GitHub Issue #48" do
     def union : Int32 | String
       42.as(Int32 | String)
     end
+
+    def capture(&block : -> T) forall T
+      block
+    end
+
+    def capture(thing : T, &block : T -> T) forall T
+      block.call(thing)
+      block
+    end
   end
 
   mock Test, make_nilable: nil
@@ -95,4 +104,22 @@ Spectator.describe "GitHub Issue #48" do
     allow(fake).to receive(:union).and_return(:test)
     expect { fake.union }.to raise_error(TypeCastError, /Symbol/)
   end
+
+  it "handles captured blocks" do
+    proc = ->{}
+    allow(fake).to receive(:capture).and_return(proc)
+    expect(fake.capture { nil }).to be(proc)
+  end
+
+  it "raises on type cast error with captured blocks" do
+    proc = ->{ 42 }
+    allow(fake).to receive(:capture).and_return(proc)
+    expect { fake.capture { "other" } }.to raise_error(TypeCastError, /Proc\(String\)/)
+  end
+
+  it "handles captured blocks with arguments" do
+    proc = ->(x : Int32) { x * 2 }
+    allow(fake).to receive(:capture).and_return(proc)
+    expect(fake.capture(5) { 5 }).to be(proc)
+  end
 end