Reland "Renamed SkSL "offset" to "line""

This reverts commit cc91452f0a65f261283615db9ed3d37b1c3acd15.

Change-Id: I7eff0ddeebef4ce298893f9b3ba410b09647e9a4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/453138
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/src/sksl/ir/SkSLPostfixExpression.cpp b/src/sksl/ir/SkSLPostfixExpression.cpp
index 05758fc..98241bd 100644
--- a/src/sksl/ir/SkSLPostfixExpression.cpp
+++ b/src/sksl/ir/SkSLPostfixExpression.cpp
@@ -19,7 +19,7 @@
                                                        Operator op) {
     const Type& baseType = base->type();
     if (!baseType.isNumber()) {
-        context.fErrors->error(base->fOffset,
+        context.fErrors->error(base->fLine,
                                "'" + String(op.operatorName()) + "' cannot operate on '" +
                                baseType.displayName() + "'");
         return nullptr;