Runtime asserts are were previously a bit annoying to debug, due to
the lack of a useful error message, even in debug mode. This patch
prints out some more information in debug mode for runtime assert
failures while preserving their exception-throwing semantics. While
we're at it, it requires a semicolon after RUNTIME_ASSERT macro
invocations.

```
$ rlwrap out/Debug/d8 --allow-natives-syntax
V8 version 5.1.0 (candidate)
d8> %ArrayBufferNeuter(1)

#
# Runtime error in ../../src/runtime/runtime-typedarray.cc, line 52
#
# args[0]->IsJSArrayBuffer()

==== C stack trace ===============================

 1: 0xf70ab5
 2: 0xadeebf
 3: 0xadedd4
 4: 0x2ef17630693b
(d8):1: illegal access
%ArrayBufferNeuter(1)
^

d8>
```

Also give the other 'illegal access' case (a special SyntaxError type) a more
descriptive error message for its sole usage.

R=adamk

Review URL: https://codereview.chromium.org/1748183002

Cr-Commit-Position: refs/heads/master@{#34401}