Add Make factory functions to basic statements.

These are the simple cases like `break` and `continue` which don't have
any optimization opportunities, types to coerce, or errors to report.
We now have Make functions for consistency across our IRNodes, but they
don't contain any interesting logic.

Change-Id: Iefdb8e3dad66f131dc892f4a7dc647246bf2554e
Bug: skia:11342
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/383707
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
diff --git a/src/sksl/SkSLRehydrator.cpp b/src/sksl/SkSLRehydrator.cpp
index ce02ed3..c3bd292 100644
--- a/src/sksl/SkSLRehydrator.cpp
+++ b/src/sksl/SkSLRehydrator.cpp
@@ -355,11 +355,11 @@
                                            isScope);
         }
         case Rehydrator::kBreak_Command:
-            return std::make_unique<BreakStatement>(/*offset=*/-1);
+            return BreakStatement::Make(/*offset=*/-1);
         case Rehydrator::kContinue_Command:
-            return std::make_unique<ContinueStatement>(/*offset=*/-1);
+            return ContinueStatement::Make(/*offset=*/-1);
         case Rehydrator::kDiscard_Command:
-            return std::make_unique<DiscardStatement>(/*offset=*/-1);
+            return DiscardStatement::Make(/*offset=*/-1);
         case Rehydrator::kDo_Command: {
             std::unique_ptr<Statement> stmt = this->statement();
             std::unique_ptr<Expression> expr = this->expression();
@@ -390,15 +390,11 @@
         case Rehydrator::kInlineMarker_Command: {
             const FunctionDeclaration* funcDecl = this->symbolRef<FunctionDeclaration>(
                                                           Symbol::Kind::kFunctionDeclaration);
-            return std::make_unique<InlineMarker>(funcDecl);
+            return InlineMarker::Make(funcDecl);
         }
         case Rehydrator::kReturn_Command: {
             std::unique_ptr<Expression> expr = this->expression();
-            if (expr) {
-                return std::make_unique<ReturnStatement>(std::move(expr));
-            } else {
-                return std::make_unique<ReturnStatement>(/*offset=*/-1);
-            }
+            return ReturnStatement::Make(/*offset=*/-1, std::move(expr));
         }
         case Rehydrator::kSwitch_Command: {
             bool isStatic = this->readU8();