Revert "Check old compiler stub after main switch statement"

This reverts commit c553490.

My Blocks Plus needs this

Author: GarboMuffin

src/compiler/irgen.js

@@ -98,7 +98,11 @@ class ScriptTreeGenerator {
             }
         }
 
-        this.oldCompilerStub = new oldCompilerCompatiblity.ScriptTreeGeneratorStub(this);
+        this.oldCompilerStub = (
+            oldCompilerCompatiblity.enabled ?
+                new oldCompilerCompatiblity.ScriptTreeGeneratorStub(this) :
+                null
+        );
     }
 
     setProcedureVariant (procedureVariant) {
@@ -202,6 +206,13 @@ class ScriptTreeGenerator {
      * @returns {IntermediateInput} Compiled input node for this input.
      */
     descendInput (block, preserveStrings = false) {
+        if (this.oldCompilerStub) {
+            const oldCompilerResult = this.oldCompilerStub.descendInputFromNewCompiler(block);
+            if (oldCompilerResult) {
+                return oldCompilerResult;
+            }
+        }
+
         switch (block.opcode) {
         case 'colour_picker':
             return this.createConstantInput(block.fields.COLOUR.value, true);
@@ -566,14 +577,7 @@ class ScriptTreeGenerator {
                 if (compatBlocks.inputs.includes(block.opcode)) {
                     return this.descendCompatLayerInput(block);
                 }
-
-                // It might be an extension block using patches for the old compiler.
-                const oldCompilerResult = this.oldCompilerStub.descendInputFromNewCompiler(block);
-                if (oldCompilerResult) {
-                    return oldCompilerResult;
-                }
-
-                // It might be an extension block using the default compatibility layer.
+                // It might be an extension block.
                 const blockInfo = this.getBlockInfo(block.opcode);
                 if (blockInfo) {
                     const type = blockInfo.info.blockType;
@@ -603,6 +607,13 @@ class ScriptTreeGenerator {
      * @returns {IntermediateStackBlock} Compiled node for this block.
      */
     descendStackedBlock (block) {
+        if (this.oldCompilerStub) {
+            const oldCompilerResult = this.oldCompilerStub.descendStackedBlockFromNewCompiler(block);
+            if (oldCompilerResult) {
+                return oldCompilerResult;
+            }
+        }
+
         switch (block.opcode) {
         case 'control_all_at_once':
             // In Scratch 3, this block behaves like "if 1 = 1"
@@ -944,14 +955,7 @@ class ScriptTreeGenerator {
                 if (compatBlocks.stacked.includes(block.opcode)) {
                     return this.descendCompatLayerStack(block);
                 }
-
-                // It might be an extension block using patches for the old compiler.
-                const oldCompilerResult = this.oldCompilerStub.descendStackedBlockFromNewCompiler(block);
-                if (oldCompilerResult) {
-                    return oldCompilerResult;
-                }
-
-                // It might be an extension block using the default compatibility layer.
+                // It might be an extension block.
                 const blockInfo = this.getBlockInfo(block.opcode);
                 if (blockInfo) {
                     const type = blockInfo.info.blockType;

src/compiler/old-compiler-compatibility.js

@@ -15,7 +15,6 @@
  *    opaque objects.
  *  - Extensions need to implement the JS generators for all AST node kinds
  *    they use. Can not rely on the defualt JS generator.
- *  - Extensions do not try to override the behavior of native blocks.
  */
 
 const {InputOpcode, InputType} = require('./enums');
@@ -347,6 +346,7 @@ JSGeneratorStub.unstable_exports = {
 };
 
 const oldCompilerCompatibility = {
+    enabled: false,
     IRGeneratorStub,
     ScriptTreeGeneratorStub,
     TypedInput,

src/virtual-machine.js

@@ -244,7 +244,10 @@ class VirtualMachine extends EventEmitter {
 
             i_will_not_ask_for_help_when_these_break: () => {
                 this.emit('LEGACY_EXTENSION_API', 'i_will_not_ask_for_help_when_these_break');
+
                 const oldCompilerCompatibility = require('./compiler/old-compiler-compatibility.js');
+                oldCompilerCompatibility.enabled = true;
+
                 return {
                     IRGenerator: oldCompilerCompatibility.IRGeneratorStub,
                     ScriptTreeGenerator: oldCompilerCompatibility.ScriptTreeGeneratorStub,