Implement execution of finally block. Fixes #1306.

bytecode/src/bytecode.rs

@@ -187,11 +187,15 @@ pub enum Instruction {
         handler: Label,
     },
 
+    /// Enter a finally block, without returning, excepting, just because we are there.
+    EnterFinally,
+
     /// Marker bytecode for the end of a finally sequence.
     /// When this bytecode is executed, the eval loop does one of those things:
     /// - Continue at a certain bytecode position
     /// - Propagate the exception
     /// - Return from a function
+    /// - Do nothing at all, just continue
     EndFinally,
 
     SetupExcept {
@@ -493,6 +497,7 @@ impl Instruction {
             SetupLoop { start, end } => w!(SetupLoop, label_map[start], label_map[end]),
             SetupExcept { handler } => w!(SetupExcept, label_map[handler]),
             SetupFinally { handler } => w!(SetupFinally, label_map[handler]),
+            EnterFinally => w!(EnterFinally),
             EndFinally => w!(EndFinally),
             SetupWith { end } => w!(SetupWith, end),
             CleanupWith { end } => w!(CleanupWith, end),