Removed unnecessary code from DSLExpression

This ReportErrors call is fairly heavy (we create a lot of expressions)
and no longer appears to be necessary given the error handling changes
elsewhere.

Change-Id: Ib9433e4346104e31e7577d6fe4b10208a277a9ff
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/448936
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

src/sksl/dsl/DSLExpression.cpp

@@ -34,8 +34,6 @@ DSLExpression::DSLExpression(DSLExpression&& other)
 DSLExpression::DSLExpression(std::unique_ptr<SkSL::Expression> expression)
     : fExpression(std::move(expression)) {
     SkASSERT(this->hasValue());
-    DSLWriter::ReportErrors(PositionInfo::Offset(nullptr, GetErrorReporter().source(),
-            fExpression->fOffset));
 }
 
 DSLExpression::DSLExpression(float value, PositionInfo pos)