Split TIntermBlock from TIntermAggregate The new TIntermBlock node class replaces TIntermAggregate nodes with the EOpSequence op. It represents the root node of the tree which is a list of declarations and function definitions, and any code blocks that can be denoted by curly braces. These include function and loop bodies, and if-else branches. This change enables a bunch of more compile-time type checking, and makes the AST code easier to understand and less error-prone. The PostProcess step that used to be done to ensure that the root node is TIntermAggregate is removed in favor of making sure that the root node is a TIntermBlock in the glslang.y parsing code. Intermediate output formatting is improved to print the EOpNull error in a clearer way. After this patch, TIntermAggregate is still used for function definitions, function prototypes, function parameter lists, function calls, variable and invariant declarations and the comma (sequence) operator. BUG=angleproject:1490 TEST=angle_unittests, angle_end2end_tests Change-Id: I04044affff979a11577bc1fe75d747e538b799c8 Reviewed-on: https://chromium-review.googlesource.com/393726 Commit-Queue: Olli Etuaho <oetuaho@nvidia.com> Reviewed-by: Corentin Wallez <cwallez@chromium.org>