Revert "Renamed SkSL "offset" to "line""

This reverts commit 58d47fa1ec2c2e7dd77ad48194801375275a401c.

Reason for revert: Tree broken

Original change's description:
> Renamed SkSL "offset" to "line"
>
> https://skia-review.googlesource.com/c/skia/+/451419 changed the meaning
> of "offset" throughout SkSL, so that it was actually tracking line
> numbers rather than offsets (and thus had a misleading name). This
> completes the transition by renaming all of the now-misnamed "offset"
> fields, parameters, and variables to "line'.
>
> Bug: skia:12459
> Change-Id: I394e6441f6ddfaad6d4098352ba9b1bfeaf273be
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/450644
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
> Reviewed-by: John Stiles <johnstiles@google.com>

Bug: skia:12459
Change-Id: Idcec3b65cb81d51c8b860c4388578700030b40a9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/452718
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
diff --git a/src/sksl/codegen/SkSLGLSLCodeGenerator.cpp b/src/sksl/codegen/SkSLGLSLCodeGenerator.cpp
index 257c49c..d4479db 100644
--- a/src/sksl/codegen/SkSLGLSLCodeGenerator.cpp
+++ b/src/sksl/codegen/SkSLGLSLCodeGenerator.cpp
@@ -780,7 +780,7 @@
             if (this->caps().fbFetchSupport()) {
                 this->write(this->caps().fbFetchColorName());
             } else {
-                fContext.fErrors->error(ref.fLine,
+                fContext.fErrors->error(ref.fOffset,
                                         "sk_LastFragColor requires framebuffer fetch support");
             }
             break;
@@ -909,12 +909,12 @@
     if (b.getOperator().kind() == Token::Kind::TK_LOGICALAND) {
         this->writeExpression(*b.right(), Precedence::kTernary);
     } else {
-        Literal boolTrue(/*line=*/-1, /*value=*/1, fContext.fTypes.fBool.get());
+        Literal boolTrue(/*offset=*/-1, /*value=*/1, fContext.fTypes.fBool.get());
         this->writeLiteral(boolTrue);
     }
     this->write(" : ");
     if (b.getOperator().kind() == Token::Kind::TK_LOGICALAND) {
-        Literal boolFalse(/*line=*/-1, /*value=*/0, fContext.fTypes.fBool.get());
+        Literal boolFalse(/*offset=*/-1, /*value=*/0, fContext.fTypes.fBool.get());
         this->writeLiteral(boolFalse);
     } else {
         this->writeExpression(*b.right(), Precedence::kTernary);
@@ -1284,8 +1284,8 @@
     if (f.test()) {
         if (this->caps().addAndTrueToLoopCondition()) {
             std::unique_ptr<Expression> and_true(new BinaryExpression(
-                    /*line=*/-1, f.test()->clone(), Token::Kind::TK_LOGICALAND,
-                    Literal::MakeBool(fContext, /*line=*/-1, /*value=*/true),
+                    /*offset=*/-1, f.test()->clone(), Token::Kind::TK_LOGICALAND,
+                    Literal::MakeBool(fContext, /*offset=*/-1, /*value=*/true),
                     fContext.fTypes.fBool.get()));
             this->writeExpression(*and_true, Precedence::kTopLevel);
         } else {
@@ -1356,7 +1356,7 @@
 void GLSLCodeGenerator::writeSwitchStatement(const SwitchStatement& s) {
     if (fProgram.fConfig->strictES2Mode()) {
         // TODO(skia:12450): write switch compatibility code
-        fContext.fErrors->error(s.fLine, "switch statements are not supported");
+        fContext.fErrors->error(s.fOffset, "switch statements are not supported");
     }
 
     this->write("switch (");