Revert "Revert "Switch to the new SkSL lexer.""

This reverts commit 358515491a0d6891e6a709688a30ad087df1beb1.

Bug: skia:
Change-Id: I013fac0ed83774d8ae7c6ee6819045cab37f5e97
Reviewed-on: https://skia-review.googlesource.com/45180
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/sksl/ast/SkSLASTIndexSuffix.h b/src/sksl/ast/SkSLASTIndexSuffix.h
index 31142e3..cb19e54 100644
--- a/src/sksl/ast/SkSLASTIndexSuffix.h
+++ b/src/sksl/ast/SkSLASTIndexSuffix.h
@@ -18,12 +18,12 @@
  * 'float[](5, 6)' are represented with a null fExpression.
  */
 struct ASTIndexSuffix : public ASTSuffix {
-    ASTIndexSuffix(Position position)
-    : INHERITED(position, ASTSuffix::kIndex_Kind)
+    ASTIndexSuffix(int offset)
+    : INHERITED(offset, ASTSuffix::kIndex_Kind)
     , fExpression(nullptr) {}
 
     ASTIndexSuffix(std::unique_ptr<ASTExpression> expression)
-    : INHERITED(expression ? expression->fPosition : Position(), ASTSuffix::kIndex_Kind)
+    : INHERITED(expression ? expression->fOffset : -1, ASTSuffix::kIndex_Kind)
     , fExpression(std::move(expression)) {}
 
     String description() const override {