[kernel] Delete most of the AST

pkg/kernel/binary.md

 This file describes the binary format of Dart Kernel.
 
 Notation
 --------
 Bitmasks are described with the syntax:
 ```scala
     Byte flags (flag1, flag2, ..., flagN)
 ```
 where 'flag<N>' is the N-th least significant bit,
 (so flag1 is the least significant bit).
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   Byte byte2(xxxxxxxx); // least signficant byte
 }
 
 type UInt30 extends UInt {
   Byte byte1(11xxxxxx); // most significant byte, discard the two high bits.
   Byte byte2(xxxxxxxx);
   Byte byte3(xxxxxxxx);
   Byte byte4(xxxxxxxx); // least significant byte
 }
 
-type MagicWord = big endian 32-bit unsigned integer
+type UInt32 = big endian 32-bit unsigned integer
 
 type List<T> {
   UInt length;
   T[length] items;
 }
 
 // Untagged pairs.
 type Pair<T0, T1> {
   T0 first;
   T1 second;
@@ skipping 54 matching lines @@
 type CanonicalNameReference {
   UInt biasedIndex; // 0 if null, otherwise N+1 where N is index of parent
 }
 
 type CanonicalName {
   CanonicalNameReference parent;
   StringReference name;
 }
 
 type ProgramFile {
-  MagicWord magic = 0x90ABCDEF;
+  UInt32 magic = 0x90ABCDEF;
   StringTable strings;
   UriSource sourceMap;
   List<CanonicalName> canonicalNames;
   List<Library> libraries;
   ProcedureReference mainMethod;
+  ProgramIndex programIndex;
+}
+
+// Program index with all fixed-size-32-bit integers.
+// This gives "semi-random-access" to certain parts of the binary.
+// By reading the last 4 bytes one knows the number of libaries,
+// which allows to skip to any other field in this program index,
+// which again allows to skip to what it points to.
+type ProgramIndex {
+  UInt32 binaryOffsetForSourceTable;
+  UInt32 binaryOffsetForCanonicalNames;
+  UInt32 mainMethodReference; // This is a ProcedureReference with a fixed-size integer.
+  UInt32[libraryCount] libraryOffsets;
+  UInt32 libraryCount;
 }
 
 type LibraryReference {
   // Must be populated by a library (possibly later in the file).
   CanonicalNameReference canonicalName;
 }
 
 type ClassReference {
   // Must be populated by a class (possibly later in the file).
   CanonicalNameReference canonicalName;
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   Option<DartType> bound;
 }
 
 type TypeParameter {
   // Note: there is no tag on TypeParameter
   StringReference name; // Cosmetic, may be empty, not unique.
   DartType bound; // 'dynamic' if no explicit bound was given.
 }
 
 ```